Class 7

MP Board Class 7th Science Solutions Chapter 9 Soil

Soil Intext Questions

Question 1.
I wonder why I found some pieces of plastic articles and polythene bags in the soil sample collected from the roadside and the garden?
Answer:
It is because people throw used plastic things and polythene bags in the soil.

Question 2.
I want to know whether ‘the soil from a field can be used to make toys?
Answer:
Yes.

Question 3.
I want to know: What kind of soil should be used for making making  and surahis?
Answer:
Clayey soil.

Question 4.
Boojho wondered why there was a difference in the absorption of water in the two squares?
Answer:
Because different soils are used to make the two squares.

Question 5.
What is the difference between rate of percolation and the amount of water retained?
Answer:
Rate of percolation is the amount of water percolated per unit time through soil. Whereas the amount of water retained is the amount of water absorbed by soil. Thus, rate of percolation and water retention are opposite attributes.

Activities

Activity 1
Collect some soil samples and observe them carefully. You can use a hand lens. Examine each sample carefully and fill in Table. Answer:
Table

Activity 2
Take a little soil. Break the clumps with your hand to powder it. Now take a glass tumbler, three quarters filled with water, and then add a handful of soil to it. Stir it well with a stick to dissolve the soil. Now let it stand undisturbed for some time. Afterwards, observe it and answer the following questions:

1. Do you see layers of particles of different sizes in the glass tumbler?
2. Draw a diagram showing these layers?
3. Are there some dead rotting leaves or animal remains floating on water?

Answer:

1. Yes
2. 
3. Yes

Activity 3
Find from your teachers, parents and farmers the type of soils and crops grown in your area. Enter the data in the following Table,

1. Which kind of soil would be most suitable for planting rice?
2. Soil with a higher or lower rate of percolation?

Answer:

1. Loamy soil.
2. Lower rate of percolation.

Soil Text Book Exercises

Tick the most suitable answer in questions 1 and 2.

Question 1.
In addition to the rock particles, the soil contains?

1. Air and water
2. Water and plants
3. Minerals, organic matter, air and water
4. Water, air and plants.

Answer:
3. Minerals, organic matter, air and water.

Question 2.
The water holding capacity is the highest in?

1. Sandy soil
2. Clayey soil
3. Loamy soil
4. Mixute of sand and loam.

Answer:
2. Clayey soil.

Question 3.
Match the items in Column I with Column II:

Answer:

(i) (b)
(ii) (c)
(iii) (a)
(iv) (e)
(v) (d).

Question 4.
Explain how soil is formed?
Answer:
The soil is the mtter which cover the top most layer of the earth in most of area. It is one of the most important natural resources. Long ago earth was a very hot sphere and then converted into a very hard and rocky land. These rocks were broken into smaller pieces by violent earthquakes. Volcanic eruptions also made the rocks and lava into smaller pieces. In cold temperatures the ice in the services of rocks expanded to break it into smaller pieces and thus gradually the soil was formed. The nature of any soil depends upon the rocks from which it has been formed and the type of vegetation that grows in it.

Question 5.
How is clayey soil useful for crops?
Answer:
Clayey soil is good at retaining water. They, are rich in humus and are very fertile. They also hold sufficient water due to the presence of smaller particles and certain enough air due to the presence of some large particles.

Question 6.
List the differences between clayey soil and sandy soil?
Clayey soil:

1. They contains more than 50% of clay particles.
2. Water holding capacity is very high.
3. Suitable for plant growth.
4. Low percolation rate.

Sandy Soil:

1. They contains about 60% of sand particles.
2. Water holding capacity is very low.
3. Not suitable for plant growth.
4. High percolation rate.

Question 7.
Sketch the cross section of soil and label the various layers?
Answer:

Question 8.
Razia conducted an experiment in the field related to the rate of percolation. She observed that it took 40 min for 200 mL of water to percolate through the soil sample. Calculate the rate of percolation.
Answer:
We know that,

Thus, the rate of percolation is 5ml/min.

Question 9.
Explain how soil pollution and soil erosion could be prevented?
Answer:
Polythene bags and plastics pollute the soil. They also kill the organisms living in the soil. That is why there is a demand to ban the polythene bags and plastics. Other substances which pollute the soil are a number of waste product, chemicals and pesticides. Waste products and chemicals should be treated before they are released into the soil.

The use of pesticides should be minimised. Soil erosion can be slowed down and soil can be conserved by regulating the factors responsible for it. Some methods to prevent or slow down the soil erosion are:

1. To stop the unnecessary cutting of forests and trees.
2. To stop the excessive use of grass land due to overgrazing by cattle.
3. Growing vegetation along the boundary of the fields and open grounds.
4. Making use of proper and scientific methods for cultivation such as crops rotation. This maintains the natural fertility of the soil and at the same time soil also maintains its capacity to hold water. Soil remains wet and cannot be easily carried away by water and blown up by wind.
5. Making use of scientific methods for irrigation and water drainage.
6. Gutting the hill slopes into steps or terraces and adopting terrace cultivation on hill slopes.

Question 10.
Solve the following crossword puzzle with the clues given:

Across:

2. Plantation prevents it.
5. Use should be banned to avoid soil pollution.
6. Type of soil used for making pottery.
7. Living organism in the soil.

Down:

1. In desert soil erosion occurs through.
3. Clay and loam are suitable for cereals like.
4. This type of soil can hold very little water.
5. Collective name for layers of soil.

Answer:

Soil Additional Important Questions

Soil Objective Type Questions

Question 1.
Choose the correct alternative:

Question (i)
The constituents of the soil are –
(a) Mineral particles, air and water
(b) Living of organisms
(c) Organic and inorganic substances
(d) All of these.
Answer:
(d) All of these.

Question (ii)
Soil is the thin layer of fine material containing –
(a) Organic matter
(b) Air and water
(c) Weathered rock materials
(d) All of these.
Answer:
(d) All of these.

Question (iii)
Soil formation is brought about by –
(a) physical factors
(b) Chemical factors
(c) Biological agent
(d) All of these.
Answer:
(d) All of these.

Question (iv)
Which profile contains humus –
(a) A – horizon
(b) B – horizon
(c) C – horizon
(d) R – horizon.
Answer:
(a) A – horizon

Question (v)
Which of these has the smallest size of particles –
(a) Sand
(b) Silt
(c) Clay
(d) Gravel.
Answer:
(b) Silt

Question (vi)
What kind of soil is best for growing cotton –
(a) Black soil
(b) Alluvial soil
(c) Red laterite soil
(d) Mountain soil.
Answer:
(a) Black soil

Question (vii)
What kind of soil is good for growing tea and coffee –
(a) Red laterite soil
(b) Black soil
(c) Laterite soil
(d) Mountain soil.
Answer:
(c) Laterite soil

Question (viii)
The dead and decaying organisms are –
(a) Humus
(b) Gravel
(c) Clay
(d) Inorganic material.
Answer:
(a) Humus

Question (ix)
Which kind of soil is best for growing wheat, rice and sugarcane –
(a) Black soil
(b) Mountain soil
(c) Alluvial soil
(d) Desert soil
Answer:
(c) Alluvial soil

Question 2.
Fill in the blanks:

1. Wheat and rice grow best in …………… soil.
2. Humus is present in the ………….. layer of soil, known as the ………….. horizon.
3. Clay is the smallest size of particles less than …………… in diameter.
4.  …………… is a mixture of sand, silt, clay and humus.
5. Weathering of rocks is a …………… process.
6. …………… is the breaking down of rocks into smaller pieces.
7. Soil commonly found in India is of …………….. main types.
8. Red colour of the soil is due to ………………

Answer:

1. Alluvial
2. Upper, A
3. 0.002 mm
4. Loam
5. Slow
6. Weathering
7. Six
8. Iron.

Question 3.
Which of the following statements are true (T) or false (F):

1. The soil is uppermost layer of the land surface.
2. The soil with particle size greater than 2 mm in diameter is gravel.
3. The soil with particle size greater than 2 mm in diameter is clay.
4. Decayed organic matter in the soil forms humus.
5. Most fertile farm lands consist of alkaline soil.
6. No humus is present in C – horizon.
7. Black soil is rich in iron and magnesium.
8. B – horizon is the most fertile part of the soil.
9. Laterite soil is rich in nutrients.
10. Soil is classified in sand, silt and clay.
11. The process of .carrying away of top soil by natural process is called soil erosion.
12. Black soil is loamy in texture with plenty of humus.
13. Overgrasing is a means of soil conservation.
14. Extremely acidic soil supports plants.
15. Planting of trees in a large area is known as afforestation.

Answer:

1. True (T)
2. True (T)
3. False (F)
4. True (T)
5. False (F)
6. True (T)
7. True (T)
8. False (F)
9. True (T)
10. True (T)
11. True (T)
12. False (F)
13. False (F)
14. False (F)
15. True (T).

Match the items in Column A with items in Column B:

Answer:

(i) (d)
(ii) (c)
(iii) (a)
(iv) (b)
(v) (e).

Soil Very Short Answer Type Questions

Question 1.
Mention two main components of soil?
Answer:
The two main components of soil are mineral particles and organic particles.

Question 2.
Name the different types of particles present in the soil?
Answer:
The different types of particles present in the soil are water, air, humus, mineral particles and living organisms.

Question 3.
What is soil?
Answer:
The soil is the outer layer of earth’s crust capable of supporting plant growth.

Question 4.
Mention two functions of soil?
Answer:
The two functions of soil are:

1. It provides water and minerals to the plants.
2. It provides anchorage to the plants.

Question 5.
What is the role of plants in the formation of soil?
Answer:
The roots of plants on penetrating into the crevices of rocks break these and help in the formation of soil.

Question 6.
Name some of the living organisms which are present in the soil?
Answer:
Fungi, bacteria, earth worms, round worms, and protozoams are the living organisms present in the soil.

Question 7.
What do you mean by soil texture?
Answer:
The structure or texture of soil determines the relative proportion of particles of different sizes.

Question 8.
What is the difference between soil texture and structure?
Answer:
Soil texture pertains to particle size, composition of a soil and soil structure refers to arrangement of soil particles into aggregates.

Question 9.
What is meant by the term weathering?
Answer:
Weathering is the breaking down of huge pieces of rocks into smaller pieces by the action of natural forces, such as water, wind, glaciers and roots of plants.

Question 10.
Which layer of soil contains the largest rock pieces?
Answer:
Bedrock contains the. largest rock pieces.

Question 11.
Which layer of soil will have the highest humus content and which the least?
Answer:
The upper most layer (A-horizon) will have the highest humus content and lowest layer (C-horizon) will have the least.

Question 12.
Which types of soil is most suitable for crops like wheat, rice and sugarcane?
Answer:
Alluvial soils is the most suitable for crops like wheat, rice x – and sugarcane.

Question 13.
Define residual soil?
Answer:
The soil which remains at the place of its formation is called residual soil.

Question 14.
Which soil is classified as alluvial type?
Answer:
The soil transported by flowing water is classified as alluvial type.

Question 15.
What are mountainous soil?
Answer:
Mountainous soil consist of clay, shales, sandstones and limestones. This type of soil is usually found in depressions and valley basins or on gently inclined slopes.

Question 16.
Define loam?
Answer:
Loam is a mixture of sand, silt and clay and also has humus in it.

Question 17.
What is soil pollution?
Answer:
The contamination of soil with excess of fertilizers, herbicides, weedicides, insecticides and industrial waste is called soil pollution.

Question 18.
Define soil moisture?
Answer:
Soil holds water in it, which is called soil moisture.

Question 19.
Name the three types of soil erosion?
Answer:
The three types of soil erosion are sheet erosion, gaily erosion and wind erosion.

Question 20.
How does vegetation help to prevent soil erosion?
Answer:
Flowing water and wind take away the top layer of the soil if there is no vegetation. The grasses, trees hold the soil in place.

Question 21.
How does soil erosion take place?
Answer:
Soil erosion can take place by natural processes such as floods, forest fire, winds, deforestation and overgrazing.

Question 22.
Which horizon of soil profile contains humus?
Answer:
A – horizon of soil profile contains humus.

Question 23.
Which type of soil is classified as residual soil?
Answer:
The soil, which remains at the place of its formation is called residual soil. This type of soil is generally poor in nitrogen, phosphorus and humus.

Question 24.
The soil at a given place was found to consist of sand stones, clay, shales and limestone. What is the type of the soil and how it might have formed?
Answer:
The type of the soil is mountainous soil. It might have formed, when the weathered soil particles are taken away to other places.

Soil Short Answer Type Questions

Question 1.
What does soil consist of?
Answer:
Soil consists of tiny bits of mineral particles which come from larger rocks and humus which is dark brown in colour and consists of decaying remains of plants and animals. Soil also contains water, air and living organisms such as bacteria, fungi, earth worms, round worms, and insects etc.

Question 2.
How is the soil formed? Explain in brief?
Answer:
Millions years ago, the surface of earth was very hard, rugged and rocky. In the long run, weathering of these rocks resulted in formation of soil which with the flow of river water came down to the lower plains and got deposited. Gradually it spread out on whole surface of the earth. Formation of soil is a very slow process. In this process rocks crack and break down into fine particles to form soil.

Question 3.
Define alluvial soil and its distribution?
Answer:
Alluvial soil is loamy soil which contains abundant amount of water in it. This is very fertile soil. This type of soil is very suitable for the production of wheat and rice. This soil is found in the plains of northern India, i.e., in the state of Punjab, Bihar, Haryana, Uttar Pradesh and West Bengal.

Question 4.
What are physical properties of soil?
Answer:
The physical properties of soil are:

1. Colour
2. Moisture storage capacity
3. Texture
4. Presence of living organisms
5. Porosity.

Question 5.
Give an account of the importance of physical properties of soil?
Answer:
The physical properties .of soil exert a great influecne on soil fertility. These are taken into consideration when soil is to be used as a medium for plant growth but also when soils are to be [ used as a structural material for making highways, dams, foundation for buildings as well as for the manufacture of bricks and tiles.

Question 6.
What are organic and inorganic components of soil?
Answer:
The inorganic components of soil comprise minerals which are derived from fragmentation and weathering of rocks. The porespaces formed between the mineral particles of soil are filled with water and gases. The organic component of soil comprise organic wastes, dead animals, plants and their decomposition products.

Question 7.
Explain the role of various organisms present in the soil?
Answer:
Bacteria in the soil helps in decomposing dead remains of plants and animals to make humus. Some bacteria can convert atmospheric nitrogen into water soluble nitrates which plants can easily use for their growth. Earthworms help in loosening of soil. They also improve the texture of the soil thus causing better growth of plants.

Question 8.
Name four common sources of pollution of soil?
Answer:
The common sources of pollution of soil are:

1. Excessive use of fertilisers.
2. Spraying of crops with insecticides and herbicides.
3. Garbage and other kitchen refuge.
4. Industrial wastes such as chemicals, plastic, leather, fly ash, etc.

Question 9.
Define A – horizon layer. Give also the main characteristic of A – horizon.
Answer:
A – horizon layer:
The uppermost layer of the soil is called A – horizon. It is generally known as upper soil or earth’s crust. The main characteristics of this layer of soil are as under:

1. It generally bears dark colour.
2. It contains lot of dead and decaying plant and animal matter called humus.
3. Due to presence of humus this layer is highly fertile.
4. The soil in this layer is porous, soft and has comparatively more water retaining capacity.
5. In this layer living organisms such as earth worms, insects, bacteria and fungi etc. are found.

Question 10.
Define B – horizon layer. Also give the main characteristics of B – horizon.
Answer:
B – horizon layer:
This layer lies next to A – horizon. The main characteristics of this layer of soil are as under:

1. The colour of this layer is comparatively dull.
2. This layer of soil is usually harder and more compact than the top soil.
3. This layer contains very less amount of organic matter in it.
4. This layer is rich in iron oxide and soluble mineral salts,
5. Roots of large and old trees are found in this layer.

Question 11.
Differentiate between Alluvial soils and Desert soils.
Answer:
Alluvial soils:

1. Loamy in texture with plenty of humus.
2. Very fertile, good for crops like wheat and rice.
3. In India, it is mainly found in the plains of Uttar Pradesh, Haryana, Bihar, West Bengal and in the coastal regions of Orissa and Andhra Pradesh.

Desert soils:

1. Soil sandy and porous, cannot hold much water.
2. If irrigated, crops can be grown.
3. In India, it is mainly found in Rajasthan and in some parts of Gujarat.

Soil Long Answer Type Questions

Question 1.
Describe the various steps involved in the formation of soil?
Answer:
There is a hard surface of the rocks just below the layer of the soil. In the past, these rocks were broken into smaller pieces by a process known as weathering. Weathering is the breaking down of huge pieces of rocks into smaller pieces by the action of natural forces, such as water, wind, glaciers and roots of plants, etc.

1. Rain water enters crevices of rocks. In winter, as this water freezes, it expands. This expansion breaks the rocks into smaller pieces.

2. The broken pieces roll down by the force of flowing or wind.

3. The broken pieces get converted into very fine particles, and mix with humus to form soil.

4. Roots of tree growing through rocks exert great pressure on the rocks. This causes cracks in the rocks, leading to weathering.

5. Large variation in day and night temperatures.

6. In hot and humid climates, the minerals in rocks react with oxygen of the air. Such oxidised rocks crumble to form soil.

Question 2.
Describe various types of soil on the basis of their classification?
Answer:
There are mainly six types of soil found in India. These are:

1. Red soil:
It is red in colour due to the presence of red iron oxide in it. It is poor in humus but can be made fertile by adding manure. This type of soil is generally found in southern part of. India.

2. Black soil:
It is derived from the lava of volcanic eruptions and is rich in minerals containing iron and magnesium. This type of soil is found in Maharashtra and parts of Madhya Pradesh, Gujarat and Andhra Pradesh.

3. Alluvial soil:
It is a loamy soil which contains abundant amount of water in it. This is very fertile soil. This type of soil is very suitable for the production of rice and wheat. This soil is found in the plains of northern India.

4. Desert soil:
It is grey to brown in colour. The soil is sandy and porous, and cannot hold much water. This soil is found in Rajasthan and Gujarat.

5. Mountain soil:
It has the highest humus content among all soils in India. These soils are highly, fertile. This soil is found in the Himalyan region and the north – eastern parts of India.

6. Laterite soil:
It is red in colour and good for crops such as tea, coffee and coconut. This type of soil is typical of the rainy climate and rich in nutritive elements. This soil is found in Tamil Nadu, Andhra Pradesh, Assam and Orissa.

Question 3.
Write an essay on the importance of soil?
Answer:
Soil is an important part of our earth. It is not only a natural habitat for various worms and insects but plants also grow and absorb water and minerals for their growth and development in the soil.

1. For food, clothing and shelter:
By supporting growth of plants, the soil provides us with food. Much of our clothing, such as cotton and wool, can be traced to the soil. Plants also provide us fuel, paper, medicines and wood for use in furniture and for constructing houses.

2. For minerals:
We depend on the soil for minerals. Industries use the minerals dug out from the earth to extract metals such as gold, silver, iron, etc. and for use in thousands of industries that produce various useful things for us. Minerals, such as petroleum, natural gas, and coal obtained from soil provide us fuel and many other useful things.

3. For clay:
We depend on the soil for clay which is the raw material used to make tiles, bricks, procelain and pottery.

4. For water:
We depend on the soil for water. Water that seeps into the soil is stored underground as subsoil water. We use this water for drinking and other purposes.

Question 4.
Write a note on soil erosion?
Answer:
The process of water or wind carrying away soil from one place to another is called soil erosion. Following are the main reasons for soil erosion:

1. Erosion by natural forces:
Fast moving wind generally . carries away with it the top soil from the surface of the earth. Similarly, heavy rainfall creates flood situation and fast moving water washes away with it the top fertile soils from our fields which combinely result into erosion of soil.

2. Erosion by human activities. Various human activities are responsible for erosion of soil such as cutting of forests, improper and unscientific methods of agriculture and extensive use of grass lands.

Question 5.
What are the main causes for the erosion of soil?
Answer:
The main causes for the erosion of soil are:
1. Cultivation:
Continuous cultivation of land by only one type of crop further adds to the loss of soil fertility. Once the top of soil is lost, the sub-soil becomes a part of the layer for cultivation. This layer has less nutrient retention power, organic matter and aeration.

2. Deforestation:
It is due to increasing population and increasing industrialization. Deforestation leads to flooding and soil erosion. Forested land looses one tonne of soil per year whereas unforested land looses approximately 40 times more soil.

3. Floods:
The soil taken away by flood often gets deposited in ponds, rivers and lakes’. This causes the water to become muddy and reduces the depth of ponds, rivers and lakes. It also raises their bed due to silting, which has an adverse impact on aquatic life.

4.Overgrasing:
Animal overgrase the slopes that leads to removal of vegetation cover from the soil. All these animals pulverise the soil which is easily washed away in time of heavy rainfall. By overgrasing the soil is denuded of its protective covering of roots and grass.

Question 6.
How will you demonstrate that the vegetation prevents erosion of soil?
Answer:
Take two trays or baskets. Fill them with garden soil. Grow grass or some cereal in one of them and water it properly for a few days. Now keep both the trays in a slightly inclined position by placing a brick below their one side. Let the water fall on both the trays. You will find that the water that flows from the tray with vegetation contains less amount of soil particles in it. This is due to the fact that the roots of plants bind the soil and do not allow it to flow with water.

Question 7.
Differentiate between Black soils and Red soils?
Answer:
Black soils:

1. Rich in iron and magnesium derived from basaltic rocks.
2. Soil is clayey, contains dead organic matter and water; ideal for growing cotton and sugarcane.
3. In India, it is mainly found in Maharashtra, parts of Andhra Padesh, Madhya Pradesh and Gujarat.

Red soils:

1. Red colour is due to the presence of iron oxide.
2. Poor in humas but cannot be made fertile by adding manure or fertilizers.
3. In India, it is found in interior regions of Kerala and Tamil Nadu, Southern Karnataka, Andhra Pradesh, Orissa, Eastern Madhya.

Question 8.
What are the human activities responsible for soil erosion?
Answer:
The various human activities responsible for soil erosion are:

1. Cutting of forests:
With the increase in population and civilisation, deforestation started. Deforestation disturbed the natural habitat of wild animals and at the same time, it enchanced the process of soil erosion.

2. Improper and unscientific methods of agriculture:
Improper and unscientific methods of agriculture also increase the rate of soil erosion.

3. Extensive use of grass lands:
Extensive use of grass lands due to overgrazing by cattle also reduces grass and other, vegetation on the earth which causes erosion of soil.

MP Board Class 7th Science Solutions

MP Board Class 7th Science Solutions Chapter 16 Water: A Precious Resource

Activities

Activity – 1
Given here is the rainfall map of India (Fig.) It gives the average annual rainfall in different regions of our country?

Question 1.
Are you blessed with sufficient rainfall?
Answer:
No.

Question 2.
Is there sufficient water available in your area throughout the year?
Answer:
Yes.

Question 3.
Can we attribute this to mismanagement of water resources?
Answer:
Yes.

Water: A Precious Resource Text Book Exercises

Question 1.
Mark T if the statement is true and F if it is false:

1. The freshwater stored in the ground is much more than that present in the rivers and lakes of the world.
2. Water shortage is a problem faced only by people living in rural areas.
3. Water from rivers is the only source for irrigation in the fields.
4. Rain is the ultimate source of water.

Answer:

1. True
2. False
3. False
4. True

Question 2.
Explain how groundwater is recharged?
Answer:
The ground water get recharged through the process of infiltration. The infiltration means seeping in water from rain, rivers and lakes into the empty spaces and crack deep below the ground.

Question 3.
There are ten tubewells in a lane of fifty houses. What could be the long term impact on the water table?
Answer:
The effect on the water table depends on the replenishment of the underground water. As only five families will share a tubewell, the water used for daily domestic purpose will not effect the water table as such. But if there is acute shortage of rains the water used by the families will not replenished and water table will fall down.

Question 4.
You have been asked to maintain a garden. How will you minimise the use of water?
Answer:
By collecting rain water. Also to minimise the wastage of water we will use the new technique of drip irrigation, which directly throws water at the base of plants.

Question 5.
Explain the factors responsible for the depletion of water table?
Answer:
Increasing population:
Increasing population creates demand for construction of houses, shops, offices, roads and pavements. This decreases the open areas like parks, and playgrounds. This, in turn, decreases the seepage of rainwater into the ground. What could be the consequence? Recall that a pukka floor does not allow water to seep in easily, while in a grass lawn water seeps through in no time.

Moreover a huge amount of water is required for construction work. Often groundwater is used for this purpose. So, on the one hand we are consuming more groundwater, and on the other we are allowing lesser water to seep into the ground. This results in depletion of water table. In fact, the water table in some parts of many cities has gone down to alarmingly low levels.

Increasing industries:
Water is used by all the industries. Almost everything that we use needs water somewhere in its production process. The number of industries is increasing continuously. Water used by most of the industries is drawn from the ground.

Agricultural activities:
A majority of farmers in India depend upon rains for irrigating their crops. Irrigation systems such as canals are there only in a few places. Even these systems may suffer from lack of water due to erratic rainfall. Therefore, farmers have to use groundwater for irrigation. Population pressure on agriculture forces increasing use of groundwater day by day. This results in depletion of water table.

Question 6.
Fill in the blanks with the appropriate answers:

1. The water bearing layer of the earth is …………………………
2. The process of water seepage into the ground is called ………………………
3. The water bearing layer of the earth is ………………………
4. The process of water seepage into the ground is called ………………………….

Answer:

1. Well and handpumps
2. Solid (ice), liquid (water), gas (water vapour)
3. Aquifer
4. Infiltration.

Question 7.
Which one of the following is not responsible for water shortage?

1. Rapid growth of industries
2. Increasing population
3. Heavy rainfall
4. Mismanagement of water resources.

Answer:
3. Heavy rainfall.

Question 8.
Choose the correct option. The total water –

1. In the lakes and rivers of the world remains constant.
2. Under the ground remains constant.
3. In the seas and oceans of the world remains constant.
4. Of the world remains constant.

Answer:
3. In the seas and oceans of the world remains constant.

Question 9.
Make a sketch showing groundwater and water table? Lab T it?
Answer:

Extended Learning Activities and Projects

Question 1.
Role play?
You are a water detective in your school? You have a term of six members? Survey the campus and make a note of the following:

1. Total number of taps
2. Number of taps leaking
3. Amount of water wasted due to leakage
4. Reasons of leakage
5. Corrective measures taken.

Answer:
Do yourself.

Question 2.
Groundwater pumped out?
Try to find out if there are any hand pumps in your neighborhood. Go to the owner or the users of a few of these and find out the depth at which they struck water? If there are any differences/think of the probable reason? Write a brief report and discuss it in your class. If possible, visit a place water boring is going on to install a hand pump? Watch the process carefully and find out the depth of the water table at that place?
Answer:
Do yourself.

Question 3.
Catching rainwater – Traditional methods? Form groups of 4 to 5 students in the class and prepare a report on the various traditional ways of water harvesting. If possible, use the following web link: www.rainwaterharvesting.org.?
Answer:
Do yourself.

Question 4.
Conservation of water? Carry out a campaign to conserve water at home and in the school. Design posters to remind others of the importance of water resources?
Answer:
Do yourself.

Question 5.
Create a logo? Hold a competition to create a logo or a symbol depicting water scarcity?
Answer:
Do yourself.

Water: A Precious Resource Additional Important Questions

Objective Type Questions

Question 1.
Choose the correct alternative:

Question (a)
…………………………. is celebrated as the “world water day”?
(a) 22 March
(b) 20 March
(c) 22 April
(d) 20 April.
Answer:
(a) 22 March

Question (b)
Water is a Unique substance because?
(a) It is consumable
(b) It is colourless
(c) It exits in all three states
(d) Both (a) and (b)
Answer:
(c) It exits in all three states

Question (c)
Year …………………….. was observed as the International Year of fresh water to make people aware of this dwindling natural resource?
(a) 2002
(b) 2003
(c) 2004
(d) 2005.
Answer:
(b) 2003

Question (d)
The earth’s surface is covered with water about?
(a) 70%
(b) 71%
(c) 72%
(d) 73%.
Answer:
(b) 71%

Question (e)
Main source of water on earth is –
(a) rain
(b) snow
(c) glaciers
(d) all the above.
Answer:
(a) rain

Question (f)
One of these is not a source of surface water –
(a) lake
(b) rain
(c) river
(d) spring.
Answer:
(d) spring.

Question (g)
This is level …………………. of ground water?
(a) sea level
(b) rain
(c) aquifer
(d) (b) and (c).
Answer:
(d) (b) and (c).

Question (h)
Water has maximum density at –
(a) 0°C
(b) 4°C
(c) 98.4°C
(d) 100°C.
Answer:
(b) 4°C

Question (i)
Water is –
(a) a mixture
(b) a compound
(c) an element
(d) none of these.
Answer:
(b) a compound

Question (j)
The purest form of natural water is –
(a) river
(b) sea
(c) rain
(d) spring.
Answer:
(c) rain

Question (k)
Common salt content of sea water is –
(a) 1.5%
(b) 2.5%
(c) 3.5%
(d) 10%.
Answer:
(b) 2.5%

Question 2.
Fill in the blanks:

1. The amount of water recommended by the United Nations for drinking, cooking, washing and maintaining proper hygiene is a minimum of ……………………… liters per person per day.
2. The water that is fit for use is ………………………..
3. Solid form of …………………. water, and …………… , is present as ice caps at the poles of the earth.
4. ……………………. water is present in lakes, oceans, rivers and even underground.
5. The process of seeping of water into ground is called ………………………..
6. Water in the aquifiers can be usually pumped out with the help of …………………………. or ………………………..
7. Increase in population, industrial and agricultural activities are some common factors affecting ……………………….. table.
8. The rain water can be used to recharge the …………………………
9. Bhujpur in the Kutch area of ………………….. has a very erratic rainfall.
10. ……………………… irrigation is a technique of watering plants.

Answer:

1. 50
2. Fresh water
3. Snow, ice
4. Liquid
5. Infiltration
6. Tubewells, handpumps
7. Water
8. Groundwater
9. Gujarat
10. Drip.

Question 3.
Which of the following statements are true (T) or false(F):

1. Water is essential for all living beings.
2. Water exists in three forms.
3. There is an uneven distribution of water.
4. Water shortage has become a matter of concern throughout the world.
5. The gaseous form is the water vapour present in the air around us.
6. Many villages do not have water supply system.
7. The water – table does not varies from place to place.
8. Water drawn from under the ground gets replenished by seepage of rain water.
9. Rainwater harvesting is not necessary.
10. Rajasthan is a hot and dry place.
11. Water allows sunlight to pass through it.
12. Pure water has no taste.

Answer:

1. True
2. True
3. True
4. True
5. True
6. True
7. False
8. True
9. False
10. True
11. True
12. True.

Water: A Precious Resource Very short Answer Type Questions

Question 1.
What is the most important property of water?
Answer:
The most important property of water is its ability to dissolve various substances. Hence, it is called a universal solvent.

Question 2.
What are the sources of water?
Answer:
The two main sources of natural water are surface water and underground water or subsoil water.

Question 3.
What are the different states of water?
Answer:
The different states of water are solid, liquid and gas.

Question 4.
What are the characteristics of pure water?
Answer:
The pure water is colourless, odourless, tasteless and transparent.

Question 5.
What do you mean by a resource?
Answer:
Materials that we get from the environment to meet our needs are called resources.

Question 6.
A part from water, what are the other natural resources?
Answer:
A part from water, air, forests, minerals and fossilfuels are natural resources.

Question 7.
What is the percentage of water that is available for human beings?
Answer:
Only a tiny fraction about 0.01% of total water is used by human beings.

Question 8.
List the sources of water for your daily use?
Answer:
Sources of water for our daily use are well, lakes, rivers and ponds.

Question 9.
Define saturated solution?
Answer:
A saturated solution of a solute at a given temperature is a solution which contains as much of the solute as it can dissolve at that temperature.

Question 10.
Define unsaturated solution?
Answer:
If a solution contains less of the solute than what it can dissolve at that temperature, then it is called all unsituated  solution.

Question 11.
Name three forms of water?
Answer:
Three forms of water are solid, gaseous and liquid.

Question 12.
Which is universal solvent?
Answer:
Water.

Question 13.
What is the percentage of water (by weight) that an average elephant body has?
Answer:
An average elephant body has 80% water by weight.

Question 14.
If you have sample of tap water, well water and sea water, which do you think has the highest amount of salts?
Answer:
Sea water has highest amount of salts.

Question 15.
List the salts that can be obtained from the sea?
Answer:

1. Common salt (NaCl)
2. Sodium bromide (NaBr)
3. Potassium iodide (Kl)
4. Calcium salts.

Question 16.
Which sea has the highest salinity?
Answer:
Dead sea has the highest salinity.

Question 17.
Name two gaseous fuels which are prepared from water?
Answer:
Water gas and hydrogen gas.

Question 18.
Define water table?
Answer:
The depth at which water is found at a particular place is called water table.

Question 19.
What is Bawri?
Answer:
Bawri is a traditional way of collecting water.

Question 20.
What is potable water?
Answer:
The water which is fit for drinking is called potable water.

Question 21.
Define salinity of water?
Answer:
Water which has salts dissolved in it and is salty in taste is called salinity of water.

Question 22.
Define water cycle?
Answer:
The water from the earth reaches the atmosphere and from there it ultimately comes back to land, this is known as water cycle.

Question 23.
How does water cycle help in maintaining global climate?
Answer:
Liquid water on heating turns into water vapours. Water vapour on cooling again forms liquid water. This change of state of water over and over again makes the cycle in nature.

Question 24.
How are clouds formed?
Answer:
Water vapours being lighter and rise up in the atmosphere. At the upper layer of the atmosphere, where the temperature is lower. The vapours get condensed into tiny water droplets and clouds are formed.

Question 25.
Which unwanted material could be present in the water that you get from your local water supply?
Answer:
The unwanted materials in our water supply are dust particles, germs, bacteria and many other materials as impurities.

Question 26.
Define water harvesting?
Answer:
Most of the water that we get as rainfall just flows aways. This is a waste of precious natural resource. The rainwater can be used to recharge the groundwater. This is known as water harvesting or rainwater harvesting.

Question 27.
Define drip irrigation?
Answer:
Drip irrigation is a technique of watering plants by making use of narrow tubings which deliver water directly at the base of the plant.

Water: A Precious Resource Short Answer Type Questions

Question 1.
Wrote a short note on source of water?
Answer:
Water is available to us through various sources. Rain water, lake Water, river water, sea water are some of the sources. Natural water from all these sources contain some impurities these are the dissolved minerals and salts. Apart from that, they contain some insoluble impurities too.

Question 2.
List the sources of water on the earth?
Answer:
There are two main sources of natural water:

1. Underground water
2. Surface water.
3. Underground Water: There are mainly two types of underground water –
   • (a) Well water
   • (b) Spring water.

2. Surface water:
It is of three types:

• Rain water
• River and lake water
• Sea water.

Question 3.
Write a short rote an river water?
Answer:
The river water is mainly due to rain or due to melting of snow on the mountains. The river water usually carries some suspended impurities and some soluble impurities. The soluble impurities are the dissolved salts and minerals. Apart from that they may carry certain micro – organisms and organic matter due to contamination.

Question 4.
Write a short note on sea water?
Answer:
Sea water is the largest source of natural water. But it is not fit either for drinking or for irrigation directly. This is because it contains a large number of dissolved salts of chlorides, bromides, iodides, sulphates and carbonates. The sea water is a rich source for common salt. It is recovered from sea water by evaporation and then is purified to remove the other impurities present.

Question 5.
Write a short note an underground water?
Answer:
Water present underneath the earth is tapped as it is an excellent source of pure drinking water. We usually dig wells. Depending on the geographical conditions of the place, the depth in which water is available is estimated. Well water contains some dissolved impurities.

Again the nature of the impurities depends on the geographical conditions. We also get water from springs under the earth. Such springs usually contain some dissolved mineral salts. However the spring water does not contain suspended impurities as it comes from deep under the earth.

Question 6.
Write a short note on rain water?
Answer:
It is the purest form of natural water available to us. Though the first few droplets of rain bring along with them some dust particles and micro-organisms, the later drops are free from impurities.

Question 7.
What are the properties of water?
Answer:
Properties of Water:

1. Pure water is colourless, odourless and tasteless.
2. Pure water freezes at 0 degree Celsius and boils at 100 degree celsius.
3. The density of water is 1 g/cc. It means that 1 cc of water at 1 degree Celsius weighs 1 gram.

Question 8.
What are the different ways by which water vapour is put into the atmosphere?
Answer:
The different ways by which water vapours put into atmosphere are as follows:

1. Factories and thermal stations produce a lot of steam and put is into the atmosphere.
2. Water in ponds, rivers and lakes, ocean gets evaporated due to atmospheric heat.
3. Plants throughout water vapours during respiration.

Question 9.
What makes the sea water so saline?
Answer:
Rivers flowing from different places bring water containing dissolved salts and minerals into the sea. Sea water is continuously evaporated by the heat of the sun. This evaporated water forms clouds and again fall on the earth as rain. This rain water again dissolves salts into it and goes into the sea. Thus the amount of salts in sea water goes on increasing.

Question 10.
How will you show that saline water is not fit for agriculture?
Answer:
Take two healthy plants of same type. Water both the plants separately one with ffesh water and other with saline water. Continue to water similarly for seven days and observe. The plant which was watered with saline water wilts. This shows that saline water is not fit for plants or agriculture.

Water: A Precious Resource Long Answer Type Questions

Question 1.
Draw a diagram to show water cycle?
Answer:

Question 2.
What are the causes of water scarcity?
Answer:
Causes of Water Scarcity:

1. Overpopulation
2. Over – irrigation for agriculture
3. Water pollution
4. Climatic change and variability
5. Indiscriminate cutting of forest
6. Increase in demand for water
7. Misuse of water
8. Poor water resource management
9. Disputes between the states for sharing water
10. Destruction of natural water reservoirs.

Question 3.
What are the methods to prevent water scarcity? Ans. Methods to prevent water scarcity:

1. Control population by adopting small family norms
2. Prevent misuse and wastage of water
3. Prevent water pollution
4. Replace large flush tanks with smaller ones.
5. Build dams, bunds and tanks to store rainwater.
6. Replace large flush tanks with smaller ones.
7. Recharge underground water
8. Recycle waste water for gardening
9. Follow drip irrigation or low water sprinklers for agriculture.

Question 4.
What are the effect of water scarcity on the life of people?
Answer:
Effect of water scarcity on the life of the people:

1. Long walk to fetch water.
2. Have to pay high price for buying water.
3. Low scope for generating employment.
4. Uncertainty over availability of water for agriculture.
5. Area will remain backward and neglected.
6. Increase incidents of crime.
7. More incidence of diseases due to poor sanitary conditions.
8. Fall in the productivity of animals.

MP Board Class 7th Science Solutions

MP Board Class 7th General English Essay Writing

1. Holi

India is the country where different festivals are celebrated every month. Most important festivals of India are Holi, Raksha Bandhan, Dusshera, Deepawali, Id and Christmas.

Holi is the festival of colours. People express their happiness by throwing colours on their friends, relatives and neighbours. They make fun. They use dry and wet colours.

People are lost in singing songs relating to the festival and season. They feel happy by welcoming their friends with sweetmeats and tea or coffee or cold drink. Sugarcane fields look full of cheerfulness of the farmers who work there. Grain fields look very beautiful.

Some people throw mud on one another and they shout. Everyone, small or big bears a smile on his face.

कठिन शब्द – different = अनेक; festivals = त्यौहार; celebrated = मनाये जाते हैं; express = प्रकट करना; fun = मजाक; dry and wet = सूखे और गीले; relating to = सम्बन्धित; season = मौसम; are lost = लीन हो जाते हैं; welcoming = स्वागत करके; sweetmeats = मिठाईयाँ; sugarcane fields=ईख के खेत; cheerfulness = प्रसन्नता; look = प्रतीत होते हैं; grain = अनाज; one another = एक-दूसरे पर; shout = शोर मचाते हैं; bear a smile = मुस्कुराहट लिए हुए; face = चेहरा।

2. My Hobby

“All work and no play makes Jack a dull boy.” There should be some amusement after work. A hobby is a thing which we do in our free time. There are several hobbies like singing, dancing, gardening etc. My hobby is gardening.

I have made a small garden. I grow vegetables, fruits and flowers in it. I work in my garden in the morning and in the evening. It gives me pleasure to work in the garden. It also saves money as I don’t have to buy vegetables from the market. It has also increased my knowledge of science. Gardening is a useful hobby as it controls pollution.

कठिन शब्द – amusement = मनोरंजन; pleasure = खुशी; saves = बचाना; increased = बढ़ाना; knowledge – ज्ञान; pollution = प्रदूषण; useful = उपयोगी।

3. My Pet Animal

I am fond of pet animals. Moti is my pet dog. It watches our house. It barks aloud if some stranger comes to our house. I take Moti for a morning walk daily. I throw a ball and Moti brings it back.

I feed it with bread and milk. I wash it daily. One night it started barking loudly. When we got up we saw some thieves trying to enter our house. Seeing us and Moti they ran away. Thus Moti saved us. I love Moti a lot.

कठिन शब्द – pet = पालतू; watch = निगरानी करना; feed = खिलाना; bark = भौंकना; loudly = तेज आवाज में; enter = घुसना; thieves = चोर; saved = बचाया।

4. Annual Day of My School

Every year in the month of February, ‘Annual day’ in our school in celebrated. Many students from different classes and sections participate in different games and activities. My friend Reeta from Class VII A, took part in 100 metre race. Other participants did their best. They all ran very fast but Reeta stood first in this race.

Reeta is the thinnest girl of her class but she is the strongest. She started from the very line and finished the race on it. Everyone praised her performance.

कठिन शब्द – annual day = वार्षिकोत्सव; celebrated = मनाया जाता है; different classes = भिन्न-भिन्न कक्षाओं के; sections = वर्गों के; participate = भाग लेते हैं; thinnest = सबसे पतली; strongest = सबसे अधिक ताकतवर; praised = प्रशंसा की; performance = कार्य प्रणाली के।

5. My Favourite Teacher

I study in Modern Public School, Raipur. There are many teachers in our school. But Mr. Gupta is my favourite teacher. He teaches us English. He is also our class teacher. He is smart and handsome. He works hard with his students. He helps weak students.

He teaches well. His examination results are always very good. He is both strict and kind. We obey him. He is also good at games. He plays cricket well. I like him very much.

कठिन शब्द – favourite = प्रिय; smart = चुस्त; handsome = सुन्दर; work hard = मेहनत करना; weak = कमजोर; well = अच्छा; strict = कठोर; obey = आज्ञा पालन करना।

6. A Journey by Train

In the last winter vacations my uncle invited us to spend a week in Delhi. My sister and I decided to leave for Delhi by the Taj Express.

We My sister and I reached the railway station at 4 p.m. I bought two tickets. We got into the train and occupied two seats. At 4:15 p.m. the train left Gwalior. After an hour it reached Morena. Then it started passing over the Chambal bridge very slowly. We saw the famous Chambal river and its ravines.

At 10:30 p.m. the train finally reached Nizamuddin railway station. Our uncle and aunt were waiting for us. They were very happy to see us. They took us home in their car.

कठिन शब्द – winter vacations = शीत अवकाश; invited = निमन्त्रण दिया; spend = बिताना; decide = निश्चय; reached = पहुँचे; bought = खरीदे; occupied = घेर लेना; ravines = बीहड़; wait = इन्तजार।

7. A Visit to A Market

I went to my uncle’s house in these summer vacations, in Agra. There I visited the Rajamandi Bazar with my cousin sister..

There was a large crowd in the market. All the shops were decorated with lights. There were shops of almost all articles. There were shops of gifts, garments, shoes, books, etc. Street vendors were also there selling various articles like purses, cosmetics etc. at cheaper rates.

I bought a pair of shoes and a nice dress for my sister. I really enjoyed there.

कठिन शब्द – crowd = भीड़; decorated = सजी हुई; articles = वस्तुएँ; cosmetics = सौन्दर्य प्रसाधन; enjoyed = लुल्फ उठाना

8. A Visit to a Circus

Last week my parents and I went to see the Apollo Circus. There was a huge crowd inside the tent. But we had special passes so we got a seat in front.

In the beginning there was a show of dwarfs.

They were so small in height and did such actions that everyone laughed. After that there were several small shows of different animals like monkey, elephant, lion, tiger. The ring master controlled them. There was also a belle dance. The dancers had a flexible body. In the end came the joker for whom I was waiting. He just made us laugh and laugh. I greatly enjoyed in the circus.

कठिन शब्द – special = ख़ास; dwarfs = बैन आदमी; beginning = शुरुआत में; flexible = लचीली।

9. My Best Friend

I have several friends but Raja is my best friend. He is my neighbour. He also studies in my class.

He is a very good boy. He is very intelligent. He always stands first in class. He is not proud. He helps his classmates. He is a ‘friend in need’. His father is a bank manager. His mother is a house wife.

He is good at sports and games too. He is cheerful and polite. I love him for his qualities and nature.

कठिन शब्द – several = कई; neighbour = पड़ोसी; studies = पढ़ता है; intelligent = बुद्धिमान; classmates = सहपाठी; house wife= गृहिणी; proud = घमण्डी; cheerful = प्रसन्नचित; qualities = गुण; nature = व्यवहार।

10. The Independence Day

15th August is an important day in the history of India. On this day in 1947 our country became free. It is our national festival. It is celebrated all over the country with great joy. We also celebrated it in our school this year.

All the students were in neat and clean uniforms. Our principal unfurled the national flag. We, then sang National Anthem. Some students presented different types of programmes. The principal gave speech in the end on our freedom fighters. The function was over after the distribution of sweets.

कठिन शब्द – important = महत्त्वपूर्ण; history = sfera; celebrated = 45MI; unfurled = 46<F1; freedom fighters = देशभक्त; distribution = वितरण।

11. My Mother

My mother is an ideal one. She is kind and affectionate. She loves her children very much. Whenever anyone of us falls ill,she is the one who tends and nutses the sick. Being of polished manners, she teaches us lessons on truthfulness, thrift and health. She also helps us in completing our home work. But she is strict also, and never tolerates any mischief in the house.

Her love towards her family is very great. She wishes to make her family ideal and for this she is always busy. She never neglects her duty. Out of immense love for the family she manages the kitchen, sews and washes clothes. She spares no pains in giving us comfort.

I am proud of my mother.

कठिन शब्द – affectionate = स्नेही; tends = सेवा करना; thrift = मितव्ययिता; tolerate = सहन करना; immense = अत्यधिक।

12. A policeman

A policeman looks very smart in his uniform. He is generally dressed in Khaki but policemen on traffic duty are clad in white. A policeman wears a cap with a badge of his department on his head. He wear’s a leather belt round his waist.

The duty of a policeman is very hard. He has to control traffic in the burning head of the sun and heavy rains. He has to look after the life and property of the public. He detects wrongdoers and brings them to book. He keeps law and order in the country.

The policeman is respected by public for his honesty and hard work. He, sometimes becomes impolite due to frustration caused by his hard duty. Certainly, our life and property are safe only by the presence of police force in our country.

कठिन शब्द – uniform = वेशभूषा; waist = कमर; wrong-doers = गलती करने वाले; impolite = अशिष्ट,अभद्र; frustration = निराशा कुण्ठा।

MP Board Class 7th English Solutions

MP Board Class 7th Science Solutions Chapter 18 Wastewater Story

Activities

Activity – 1
We have given one example of the use of clean water. You can add many more?

Answer:

Activity – 2
Locates an open drain near your home, school or on the roadside and inspect water flowing through it? Record color, odour and any other observation. Discuss with your friends and your teacher and fill up the following Table?
Table: Contaminant survey

Wastewater Story Text Book Exercises

Question 1.
Fill in the blanks:

1. Cleaning of water is a process of removing ……………………….
2. Waste – water released by houses is called ………………………
3. Dried ……………………… is used as manure.
4. Drains get blocked by …………………….. and ………………………..

Answer:

1. Contaminants
2. Sewage
3. Dung
4. Plastic, sludge.

Question 2.
What is sewage? Explain why it is harmful to discharge untreated sewage into rivers or seas?
Answer:
Sewage is waste – water released by homes, hospitals, offices, industries and other users. It also includes rainwater that has run down the street during a heavy rain or storm. The water that washes off roads and roof tops carries harmful substances with it. Basically sewage is a liquid waste. Most of it is water, which has dissolved and suspended impurities which are called contaminants. That is why it is harmful to discharge untreated sewage in to rivers or seas.

Question 3.
Why should oils and fats be not released in the drain? Explain.
Answer:
Oils and fats should not be released in the drains because they harden the soil in the pipes and block them. Fats get clogged in the holes of the soil in the drain and block it. It does not allow the waste – water to flow and thus the whole sewer system is blocked.

Question 4.
Describe the steps involved in getting clarified water from waste – water?
Answer:
Treatment of waste – water involves physical, chemical, and biological processes, which remove physical, chemical and biological matter that contaminates the waste – water.

1. Waste – water is passed through bar screens. Large objects like rags, sticks, cans, plastic packets, napkins are removed.

2. Water goes to a grit and sand removal tank. The speed of the incoming waste-water is decreased to allow sand, grit and pebbles to settle down.

3. The water is then allowed to settle in a large tank which is sloped towards the middle. Solids like faces settle at the bottom and are removed with a scraper. This is the sludge. A skimmer removes the float able solids like oil and grease. Water so cleared is called clarified water.

4. The sludge is transferred to a separate tank where it is decomposed by the anaerobic bacteria. The bio gas produced in the process can be used as fuel or can be used to produce electricity.

5. Air is pumped into the clarified water to help aerobic bacteria to grow. Bacteria consume human waste, food waste, soaps and other unwanted matter still remaining in clarified water. After several hours, the suspended microbes settle at the bottom of the tank as activated sludge. The water is then removed from the top.

Question 5.
What is sludge? Explain how it is treated?
Answer:
Sludge is the collected solid waste from the waste – water during the treatment in water treatment plant. Sludge is decomposed in a separate tank by the anaerobic bacteria. The activated sludge is about 97% water. The water is removed by sand drying beds or machines. Dried sludge is used as manure, returning organic matter and nutrients to the soil.

The treated water has a very low level of organic material and suspended matter. It is discharged into a sea, a river or into the ground. Nature cleans it up further. Sometimes it may be necessary to disinfect water with chemicals like chlorine and ozone before releasing it into the distribution system.

Question 6.
Untreated human excreta is a health hazard? Explain?
Answer:
Untreated human excreta is a health hazard. It may cause water pollution and soil pollution. Both the surface water and groundwater get polluted. Groundwater is a source of water for wells, tubewells, springs and many rivers. Thus, it becomes the most common route for water borne diseases. They include chlorea, typhoid, polio, meaningities, hepatitis and dysentery.

Question 7.
Name two chemicals used to disinfect water?
Answer:
Ozone, chlorine.

Question 8.
Explain the function of bar screens in a waste – water treatment plant?
Answer:
Bar screens clear the waste – water of all the physical impurities. Large waste objects like napkins, plastics, can sticks, rags etc. are removed from the waste – water through the bar screens.

Question 9.
Explain the relationship between sanitation and disease?
Answer:
Untreated human excreta is a health hazard. It may cause water pollution and soil pollution. Both the surface water and groundwater get polluted. Groundwater is a source of water for walls, tubewells, springs and many rivers. Thus, it becomes the most common route for water borne diseases. They include cholera, typhoid, polio, meningitis, hepatitis and dysentery. That is proper sanitation is must to avoid some of the deadliest diseases.

Question 10.
Outline your role as an active citizen in relation to sanitation?
Answer:
As active citizen we should take care of our personal and environmental sanitation. We should make people around us, aware of the benefits of sanitation we should help the municipal corporations and gram panchayats to cover all the open drains and remove the unhygienic and disease causing substances thrown in open.

Question 11.
Here is a crossword puzzle: Good luck!

Across

1. Liquid waste products
2. Solid waste extracted in sewage treatment
3. A word related to hygiene
4. Waste matter discharged from human body.

Down

1. Used water
2. A pipe carrying sewage.
3. Micro – organisms which causes cholera.
4. A chemical to disinfect water.

Answer:

Question 12.
Study the following statements about ozone:

1. It is essential for breathing of living organisms.
2. It is used to disinfect water.
3. It absorbs ultraviolet rays.
4. Its proportion in air is about 3%.

Which of these statements are correct?

1. (a), (b) and (c)
2. (b) and (c)
3. (a) and (d)
4. All four.

Answer:

2. (b) and (c).

Extended Learning – Activities and Projects

Question 1.
Construct a crossword puzzle of your using the keywords?
Answer:

Across:

1. Mixing with air.
2. Decomposed product of leaves.
3. Does not read oxygen
4. Needs oxygen.

Down:

1. Necessary for hygiene
2. Solid waste
3. Pipes to carry sewage

Question 2.
Then and now: Talk to your grand parents and other elderly people in the neighbourhood? Find out the sewage disposal systems available to them. You can also write letters to people living in far off places to get more information. Prepare a brief report on the information you collected?
Answer:
Do yourself.

Question 3.
Visit a sewage treatment plant?
It could be as exciting and enriching as a visit to a zoo, a museum, or a park? To guide your observation here are a few suggestions?

Record in your notepad:
Place ……………….. Date …………………… Time
Name of the official at the plant ………………………. Guide/Teacher …………………………

1. The location of the sewage plant.
2. Treatment capacity.
3. The purpose of screening as the initial process?
4. How is air bubbled through the aeration tank?
5. How safe is the water at the end of the treatment? How is it tested?
6. Where is the water discharged after treatment?
7. What happens to the plant during heavy rains?
8. Is bio gas consumed within the plant or sold to other consumers?
9. What happens to the treated sludge?
10. Is there any special effort to protect nearby houses from the plant?
11. Other observations.

Answer:
Do with the help of your subject teacher.

Wastewater Story Additional Important Questions

Objective Type Questions

Question 1.
Choose the correct alternative :

Question (a)
This is not the cause of water pollution?
(a) Floods
(b) Rains
(c) Chemicals
(d) Open defecation.
Answer:
(b) Rains

Question (b)
To improve sanitation following new technique is being used?
(a) Vermi – processing toilets
(b) Sewer system
(c) Onsite sewage disposal
(d) Both (a) and (b).
Answer:
(d) Both (a) and (b).

Question (c)
Following should not be disposed off in the drains?
(a) Tissue Papers
(b) Excreta
(c) Oils and Fats
(d) Waste water.
Answer:
(c) Oils and Fats

Question (d)
Following process is not a part of waste – water treatment?
(a) Decomposition
(b) Grit and Sand Removal
(c) Evaporation
(d) Chlorination.
Answer:
(c) Evaporation

Question (e)
Polluted water causes disease likes –
(a) Hepatitis
(b) Typhopid
(c) Cholera
(d) Diarrhoea.
Answer:
(c) Cholera

Question (f)
In a public sewerage system, the largest sewers are –
(a) Filters
(b) Interceptors
(c) Waterways
(d) None of these.
Answer:
(b) Interceptors

Question 2.
Fill in the blanks:

1. …………………… bacteria is used to treat sludge.
2. Sewage is a liquid waste which causes water and soil
3. Waste – water is treated in a sewage treatment ………………………
4. …………………… and …………………….. are the products of water clarification.
5. By – products of waste – water treatment are sludge and ………………………
6. Addition of disease causing organisms in water is called water …………………….
7. …………………………… in open cause health hazards.
8. ……………………….. is used as manure.
9. To improve sanitation, low cost ……………………….. sewage disposal systems are being encouraged.
10. Adopting good sanitation practices should be our way of ……………………………….

Answer:

1. Anaerobic
2. Pollution
3. Plant
4. Sludge and bio gas
5. Bio – gas
6. Contamination
7. Defecation
8. Activated sludge
9. Onsite
10. Life.

Question 3.
Which of the following statements are true (T) or false(F):

1. Sewage contains pure water for drinking.
2. Used water is waste – water.
3. Waste – water could not be reused.
4. Open drain system is a breeding place for flies.
5. Manholes are located at every 50 m to 60 m in the sewerage.
6. Waste – water is passed through for screens.
7. Eucalyptus trees absorb all surplus waste – water rapidly and release pure water vapour into the atmosphere.

Answer:

1. False
2. True
3. False
4. True
5. True
6. True
7. True.

Wastewater Story Very Short Answer Type Questions

Question 1.
Define sewage?
Answer:
Sewage is water that contains waste products produced by human beings. It is also called waste water.

Question 2.
Which is the world water day?
Answer:
22nd March.

Question 3.
Which is proclaimed as the International Decade for action on water for life?
Answer:
United Nations proclaimed the period 2005 – 2015 as the international Decade for action on “Water for life”.

Question 4.
What do you mean by cleaning of water?
Answer:
Cleaning of water is a process of removing pollutants before it enters a water body or is reused.

Question 5.
What is sewage treatment?
Answer:
This process of wastewater treatment is commonly known as “Sewage Treatment”.

Question 6.
In how many steps sewage treatment divided?
Answer:
The sewage treatment in most cities involve two main steps primary and secondary treatment. Some cities also require an additional step called tertiary treatment.

Question 7.
What do you mean by primary treatment?
Answer:
The primary treatment removes the heaviest solid material from sewage. This process removes about half the suspended solids and bacteria in sewage. Sometimes chlorine gas is added to kill most of the remaining bacteria.

Question 8.
What do you mean by secondary treatment?
Answer:
The secondary treatment removes from 85% to 90% of the solids and oxygen consuming wastes remaining in sewage after it has undergone primary treatment. The most common methods of secondary treatment are the activated sludge process and the trickling filtration process.

Question 9.
Why should we plant eucalyptus along sewage ponds?
Answer:
These trees absorb all surplus waste – water rapidly and release pure water vapour into the atmosphere.

Question 10.
Write certain inorganic impurities in the waste – water?
Answer:
Metals, phosphates and nitrates.

Question 11.
Name certain disease causing micro – organism?
Answer:
Bacterias, Viruses etc.

Question 12.
Which process removes the solids like faces and other substances from the waste – water?
Answer:
Grit and sand removal tank.

Question 13.
How is sand, grit on pebbles settled down?
Answer:
Water goes to a grit and sand removal tank. The speed of the incoming waste-water is decreased to allow sand, grit and pebbles to settle down.

Question 14.
How is dry sludge used?
Answer:
Dried sludge is used as manure, returning organic matter and nutrients to the soil.

Question 15.
Who decomposes the sludge?
Answer:
Anaerobic bacteria decompose the sludge.

Question 16.
Which instrument is used to remove floatable solids from the waste – water?
Answer:
A skimmer is used to remove floatable impurities.

Question 17.
What helps to clean the clarified water?
Answer:
Aerobic bacteria helps to clean the clarified water.

Question 18.
Why is ozone and chlorine used?
Answer:
Ozone and chlorine is used to kill the bacteria etc. present in the clarified water.

Question 19.
Why is air pumped to clarified water?
Answer:
Air is pumped into the clarified water to help aerobic bacteria to grow. Bacteria consume human waste, food waste, soaps and other unwanted matter still remaining in clarified water.

Wastewater Story Short Answer Type Questions

Question 1.
Explain sewage?
Answer:
Waste water including human excreta which flows from our homes into the drains is called domestic sewage. This contains microbes which cause water – borne diseases. This waste water is often dumped into water bodies.

Question 2.
How is water polluted?
Answer:
Water is used various purposes in homes, industries and agriculture. When water is used for cleaning, bathing, washing, dying etc. it pollutes the water. Unwanted waste materials and chemicals etc get added in the water and this wastes the water.

Question 3.
What is done to improve sanitation?
Answer:
To improve sanitation, low cost onsite sewage disposal stem are being encouraged. Examples are septic tanks, chemical toilets, composting pits. Septic tanks are suitable for places where there is no sewerage system, for hospitals isolated buildings or a Luster of 4 to 5 houses.

Question 4.
What is vermi process toilet?
Answer:
A design of a toilet in which humans excreta is treated by earthworms has been tested in India. It has been found to be a novel, j low water – use toilet for safe processing of human waste. The operation of the toilet is very simple and hygienic. The human excreta is completely converted to vermi cakes resource much needed for soil.

Wastewater Story Long Answer Type Questions

Question 1.
How defection in open cause health hazards?
Answer:
Due to lack of proper sewage disposal system a large amount of people in India defecates in open. They use riverbeds, railway lines, fields and drains for this purpose. These excreta dries down and percolate in soil with rain water. It pollutes the ground water.

Excreate along river bed pollutes the river water. In this way water on the ground and under the ground get polluted. This polluted water contains the micro – organisms of various communicable diseases like cholera, typhoid, hepatitis and meaning it is dysentery etc.

Question 2.
Suggest some better house keeping practices?
Answer:

1. Cooking oil and fats should not be thrown down the drain. They can harden and block the pipes. In an open drain the fats dog the soil pores redunt. Its effectiveness in filtering water. Oil and fats should he thrown in the dustbin.

2. Chemicals like paints, vents, insecticides, motor oil, medicines may kill microbes it help purity water. So they should not be thrown in the drain.

3. Used ten – leaves, solid food remains, soft toys, cotton, sanitary towels, etc. should also be thrown in the dustbin. These waste choke the drains. They do not allow free flow of oxygen. This hampers the degradation process.

Question 3.
What is the composition of sewage?
Answer:
Sewage is a complex mixture containing suspended solids, organic and inorganic impurities. nutrients, saprotrophic and disease causing bacteria and other microbes.

1. Organic impurities:
Human faces, animal waste, oil, urea (urine), pesticides, herbicides, fruit and vegetable waste, etc.

2. Inorganic impurities:
Nitrates, phosphates, metals. Nutrients Phosphorus and nitrogen.

3. Bacteria:
Such as which cause cholera and typhoid.

4. Other microbes:
Such as which cause dysentery.

Question 4.
How is sewage treated?
Answer:
Domestic sewage should be treated before being discharged into the river. Sewage is treated by first separating the solid material by sedimentation and filtration. Compressed air is then passed through the liquid which is then chlorinated to kill micro – organisms. The solid matter separated from sewage can be used to generated bio gas which can be used as fuel. The sludge that is left can be used as manure in the fields to grow organic foods.

Question 5.
What are the different ways in which solid waste can be disposed off?
Answer:
The different ways are as:

1. Domestic wastes like fruit and vegetable waste, leftover food, leaves of potted plants can be converted into compost and used as manure.
2. Most of the solid waste is buried in low lying areas to level uneven land. This is called landfill.
3. Wastes coming from industries such as metals can be recycled and used again.
4. Broken plastic articles like plastic bags, buckets, bowls, cups, plates, etc. can be melted and remolded to make new articles.
5. The waste disposal on a large scale is done by the municipality of a city using incinerators. The solid waste is burnt at high temperature. Ash is removed from time to time.

Question 6.
Explain sewage treatment plant.
Answer:
Sewage is water that contains waste products by human beings. It is also known as waste water. In fact sewage comes from the sinks and toilets of homes, restaurants, factories and office buildings. The sewage mainly consists of dissolved material that cannot be seen and bits of such solid matter as human waste and ground up rubbish.

It also contains harmful chemical and disease producting bacteria. Most sewage ultimately goes into lakes, rivers and oceans. However, in many western nations, the sewage is treated in some way before it goes into the waterways as a semi – clear liquid called effluent. Most methods used to treat sewage convert organic sewage into inorganic compounds viz. nitratres, sulphates and phosphates. Some of these compounds serve as food for algae. As the algae decay using excess of oxygen from water, the fish and plants in water will ultimately die.

Question 7.
Explain rural sewerage system?
Answer:
Many rural areas not served by public sewers. In such areas, most home owners use septic tanks to treat their sewage. These tanks are concrete or steel containers buried underground at home and buildings. Sewage flows into a septic tank through a pipe connecting the tank with a building.

Solids in the sewage sink to the bottom of the tank as sludge or float to the surface as scum. Effluent then flows from the tank into a system of pipes with open joints that allow sewage effluent to be gradually distributed into the soil. The soil bacteria then destroy the remaining organic material in the influent.

In a septic tank, bacteria in the sewage attack and digest the sludge and scum. The digestion process changes most to the wastes into gas and a harmless substance called humus. The gas then escapes into the air. The humus in the tank should be pumped our periodically and taken to a sewage treatment plant.

Question 8.
Explaining urban sewerage system?
Answer:
In a public sewerage system, the largest sewers, known as interceptors, carry the sewage to a wastewater treatment plant. The sewage treatment in most cities involves two main steps, primary treatment and secondary treatment. Some cities also require an additional step called tertiary treatment. At a treatment plant, sewage first passes through a screen that traps the largest pieces of matter. It then flows through a grit chamber, where heavy inorganic matter, such as sand, settles down.

The liquid next flows into a large primary sedimentations tank. Many suspended solids sink to the bottom of this tank and form a muddy material called sludge. Grease floats to the surface, where it is removed by a process called skimming. The effluent is then released into waterways.

Primary treatment removes bout half of the suspended solids and bacteria in sewage. Sometimes chlorine gas is added after primary or secondary treatment to kill most of the remaining bacteria. The secondary treatment removes about 85 to 90 percent of the solids and oxygen consuming wastes remaining in sewage after it has undergone primary treatment.

Question 9.
Explain the most common methods of secondary treatment in urban sewerage system?
Answer:
The most common methods of secondary treatment are:

1. The activated sludge process.
2. The trickling filtration process.

In case of activated sludge process, the influent from the primary sedimentation tank flows into a second tank called an aeration tank. The useful bacteria move through the liquid and change the organic matter into less harmful substances. The liquid then flows into a final sedimentation tank, where the sludge settles down to the bottom.

The influent is then discharged into waterways. In case of trickling filtration process, the filters are filled with crushed rocks. As sewage is distributed over the rocks, it reacts with slime that develops on the rocks. The slime contains useful bacteria that change organic material in the sewage into less harmful substances. These substances are removed in a final sedimentation tank, where they fall to the bottom as sludge.

Sometimes tertiary treatment is also used after primary and secondary treatment to produce purer effluent. The tertiary treatment methods include chemical treatment, microscopic screening, radiation treatment, etc. Tertiary treatment makes effluent safer to discharge into waterways.

MP Board Class 7th Science Solutions

MP Board Class 7th Science Solutions Chapter 17 Forests: Our Lifeline

Forests: Our Lifeline Intex Questions

Question 1.
What would happen if forests disappear?
Answer:

1. If forests disappear, the amount of carbon dioxide in air will increase, resulting in the increase of earth’s temperature.
2. In the absence of trees and plants, the animals will not get food and shelter.
3. In the absence of trees, the soil will not hold water which will cause floods.
4. Deforestation will ending our life and environment. Think, what, we can do to preserve our forests.

Forests: Our Lifeline Text Book Exercises

Question 1.
Explain how animals dwelling in the forest help it grow and regenerate?
Answer:
Animals help in growing and regenerating forests in many ways. Animals help in dispersing, seeds of certain plants. The decaying animal dung also provides nutrients to the seedling to plant. By this number of plants are growing which serve as a food for a number of herbivorous animals.

Herbivorous helps the carnivores to grow as they serve as food for them. So, the flora and fauna grows in the forests. Also, the animals work as the cleaning agents in the forest micro – organisms work on the death bodies of plants and animals and regenerate them.

Question 2.
Explain how forest prevent floods?
Answer:
If trees or widely we can say that forests are not present, rain will directly hit the ground and may cause the flood the area around it. Also, the heavy rain may damage the soil. Roots of trees and grasses basically bind the soil together, but in the absence of soil, they will be washed away or eroded.

The washed soil will get deposited in river and thus reduce the water carrying capacity of rivers. Which is the major causes of flood. Also, forests can absorb a lot of water. This also helps in preventing floods.

Question 3.
What are decomposers? Name any two of them. What do they do in the forest?
Answer:
The micro – organisms which convert the dead plants and animals to humus are known as decomposers. These micro – organisms play an important role in the forest. The any two decomposers are grubs and beetles. They clean the forests of the decaying dead bodies and replenishes the nutrient back to the forest soil.

Question 4.
Explain the role of forest in maintaining the balance between oxygen and carbon – dioxide in the atmosphere?
Answer:
Plants release oxygen through the C0₂ photosynthesis. The Plants help to provide oxygen for animal respiration. They also maintain the balance of oxygen and carbon dioxide in the atmosphere. That is why forests are called lungs.

Question 5.
Explain why there is no waste in a forest?
Answer:
The decomposers decompose the dead organisms. The decomposed matter is absorbed by plants as nutrients. Thus, there is no waste in a forest.

Question 6.
List five products we get from forests?
Answer:
We get following products from forests:

1. Medicine
2. Spice
3. Wood
4. Honey.
5. Gum

Question 7.
Fill in the blanks:

1. The insects, butterflies, honeybees and birds help flowering plants in ………………………..
2. A forest is a purifier of ……………………………. and …………………………
3. Herbs form the ……………………………… layer in the forest.
4. The decaying leaves and animal droppings in a forest enrich the ………………………….

Answer:

1. Pollination
2. Water, air
3. Lowest
4. Humus.

Question 8.
Why should we worry about the conditions and issues related to forests far from us?
Answer:
We should be worried about deforestation, as it would lead to floods, increase in earth’s temperature, depriving animals of their habitats and soil erosion.

Question 9.
Explain why there is a need of variety of animals and plants in a forest?
Answer:
Variety of animals are necessary for their survival and maintenance of food chain. For example, grass is eaten by insects, which in turn, are eaten by the frog. The frog is consumed by snakes and snakes is eaten by eagles.

Thus, it forms a food chain. There are so many food chains in the forest. All of these are linked. If any one food chain is disturbed, it affects other food chains. Also, animals convert the death plants and animals into humus and increase the fertility of soil.

Question 10.
In figure, the artist has forgotten to put the labels and directions on the arrows. Mark the directions on the arrows and label the diagram using the following labels: clouds, rain, atmosphere, carbon dioxide, oxygen, plants, animals, soil roots, water table?
Answer:

Question 11.
Which of the following is not a forest product?

1. Gum
2. Plywood
3. Sealing wax
4. Kerosene

Answer:
4. Kerosene.

Question 12.
Which of the following statements is not correct?

1. Forests protect the soil from erosion.
2. Plants and animals in a forest are not dependent on one another.
3. Forests influence the climate and water cycle.
4. Soil helps forests to grow and regenerate.

Answer:
2. Plants and animals in a forest are not dependent on one another.

Question 13.
Micro – organisms act upon the dead plants to produce?

1. Sand
2. Mushrooms
3. Humus
4. wood.

Answer:
3. humus.

Extended Learning – Activities and Projects

Question 1.
The Department of Environment is to decide whether some portion of a forest in your area could be cleared for a housing complex. Write a letter to the department explaining your point of view as a concerned citizen?
Answer:
Do yourself.

Question 2.
Visit a forest? Here is a list of points that would make your visit more fruitful?

1. Make sure that you have permission to go into the forest.
2. Make sure that you can find your way around. Get a map and go along with some one who is familiar with the area.
3. Keep a record of the things you see and do. Observations make the visit interesting. Sketches and photographs are useful.
4. You may record bird calls.
5. Collect different kinds of seeds or hard fruits like nuts.
6. Try to recognise various types of trees, shrubs, herbs, etc. Make lists of plants from different places in the forest and of different layers. You may not be able to name all the plants, but it is worth recording and seeing where they grow. Make a record of approximate heights of plants, crown shape, bark texture, leaf size, and flower colour.
7. Learn to recognise the animal’s droppings.
8. Interview the forest officials and the people of surrounding villages and other visitors.
9. You must never collect birds eggs, and their nests should never be disturbed.

Answer:
Do yourself.

Forests: Our Lifeline Additional Important Questions

Objective Type Questions

Question 1.
Choose the correct alternative:

Question (a)
Plants give out during photosynthesis?
(a) carbon dioxide
(b) oxygen
(c) humus
(d) none of these.
Answer:
(b) oxygen

Question (b)
Interdependence of animals for food is called –
(a) food – order
(b) food – cycle
(c) food – chain
(d) none of these.
Answer:
(c) food – chain

Question (c)
Small trees and grass and shrubs from the –
Answer:
(a) Canopy
(b) Under stories
(c) Lowest canopy
(d) All of these
Answer:
(b) Under stories

Question (d)
Deforestation leads to
(a) Soil erosion
(b) Floods
(c) Both of these
(d) None of these
Answer:
(c) Both of these

Question 2.
Fill in the blanks:

1. The branch part of a tree above the stem is known as the ……………………… of the tree.
2. The micro – organisms which convert the dead plants and animals to humus are known as …………………………
3. The plants help to provide ………………………….. for animal respiration.
4. The plants maintain the balance of oxygen and carbon dioxide in the …………………………
5. The covered ground with decaying material acts like a ……………………………
6. The root system helps water to seep down in the ……………………………
7. Forests protect the soil from ………………………..
8. Forests are the lifeline for the forest dwelling …………………………….

Answer:

1. Crown
2. Decomposers
3. Oxygen
4. Atmosphere
5. Sponge
6. Ground
7. Erosion
8. Communities.

Question 3.
Which of the following statements are true (T) or false (F):

1. Forests cause rain on the earth.
2. In a forests, the herbs form the lowest layer of the vegetation.
3. The various components of the forest are not interdependent on one another.
4. The forests keeps on growing and changing, and can regenerate.
5. Soils helps forests to grow and regenerate.
6. Forests influence climate, water – cycle and air quality.
7. Forests is a renewable natural resources.

Answer:

1. True
2. Ture
3. False
4. True
5. True
6. True
7. True.

Forests: Our Lifeline Very Short Answer Type Questions

Question 1.
What do you mean by forest?
Answer:
Forest is a place hosting a number of animals and plants.

Question 2.
Name any two trees in forest?
Answer:
Sheesham, Neem.

Question 3.
Write any three things we get from forests?
Answer:
Gum, medicine and wood.

Question 4.
Which plants constitute canopy in forests?
Answer:
Tall and giant trees.

Question 5.
What is the basic unit of any food chain?
Answer:
Plants.

Question 6.
Write one food chain in forest?
Answer:
Grass → Insects → Frog → Snake → Eagle

Question 7.
How is forest environment?
Answer:
Forest environment is peaceful and a cool breeze is blowing.

Question 8.
Name some animals that live deep inside forest?
Answer:
Bison, Jackals, Boar, Elephants.

Question 9.
What is humus?
Answer:
Humus is a dark coloured substance which is formed from the dead bodies of plants and animals.

Question 10.
What happens if an animal dies in the forest?
Answer:
The dead animals become food for vultures, jackals, insects and crows.

Question 11.
How does forest help in preventing floods?
Answer:
Forests absorb the rain .water in the soil and prevent the floods.

Question 12.
What is seed dispersal?
Answer:
The method by which plants scatter their seeds to reduce competition between off springs.

Question 13.
Define soil erosion?
Answer:
The weaving away of the soil by wind or water.

Question 14.
What do you mean by canopy?
Answer:
The branches of the tall trees look like a roof over the other plants in the forest is called canopy.

Question 15.
Define crown?
Answer:
Branch part of a tree above the stem is known as the crown.

Question 16.
What is deforestation?
Answer:
Cutting and destroying the forest is called deforestation.

Question 17.
What are the effects of deforestation?
Answer:
Floods, rising temperature, scarcity of flood and wood and disturbed flood chains are the results of deforestation.

Question 18.
What do you mean by afforestation?
Answer:
Planting more trees is called afforestation.

Question 19.
What would happen if it rains heavily in your town?
Answer:
There will be water logging or even flood. Everything will be in a mesh. No food, no water. No place, no stay.

Forests: Our Lifeline Short Answer Type Questions

Question 1.
Define soil erosion?
Answer:
Removal of fertile top layers of earth (soil) is called soil erosion. The soil erosion can be brought about by various agents like – water, wind, glaciers and ocean waves. Erosion occurs in both wet and arid regions. The various human activities like falling of trees, over – cropping and improper tilling accelerate soil erosion. The soil erosion can lead to floods.

Question 2.
What are the major factors that lead to soil erosion? Name them?
Answer:
The major factors that lead to soil erosion are the following:

1. Overgrazing by livestock
2. Deforestation
3. Over cultivation
4. Poor irrigation facilities
5. Water logging
6. Shifting cultivation.

Question 3.
Write about the dependence of animals on plants?
Answer:
Dependence of Animals on Plants:

1. Plants produce food by the process of photosynthesis and animals depend directly or indirectly on them for food.
2. Plants produce oxygen during photosynthesis and animals use this oxygen for respiration.
3. Plants act as habitat for the animals dwelling on trees.

Question 4.
Write about the dependence of plants on animals?
Answer:
Dependence of Plants on Animals:

1. Animals produce carbon dioxide during respiration which is released in the atmosphere. Plants use this oxygen for preparing food.
2. A number of insects, birds and bats help in pollination.
3. Some animals help in dispersal of fruits and seeds.

Question 5.
How forests help in bringing rain?
Answer:
Trees absorbs water from the soil through their roots. They then release the excess of water through the process of transpiration in the form of water vapours. These water vapours form clouds and clouds bring rain.

Question 6.
How are forests useful to us?
Answer:
The forests are very useful to us for the following reasons:

1. They conserve soil and water.
2. They are helpful in causing rains.
3. They give us food and fruit.
4. They are the natural habitats of animals.
5. They help in the maintenance of ecological balance.

Question 7.
Write a short note on deforestation?
Answer:
Deforestation is another important cause which brings about soil erosion. Deforestation leads to depletion of water vapour in the atmosphere so which in turn adversely affects the formation of rain bearing clouds and consequently the rainfall. In the absence of adequate rainfall, the soil dries up and its nutrient value is affected.

The decrease in rainfall affects the growth of plants and trees, thus leads to the formation of deserts. When there is no plant cover over the earth, it becomes naked. When rain falls over this naked earth, the water does not percolate down the earth and washes away. Similarly, strong winds also take away the top soil, thus causing soil erosion.

Question 8.
In which layer of the soil would you find humus? What is its importance to the soil?
Answer:
Humus is found in the top of layer of soil. The presence of humus ensures that the nutrients of the dead plants and animals are released into the soil. From there, these nutrients are again absorbed by the roots of the living plants.

Forests: Our Lifeline Long Answer Type Questions

Question 1.
How we can conserved the forests?
Answer:

1. Unplanned and indiscriminate deforestation must be stopped.
2. Forest should not be over – exploited.
3. Use of wood as fuel should be discouraged.
4. Plant new fast growing trees.
5. Protect forest from fires, insects and diseases.
6. Protect national parks, wildlife sanctuaries or biosphere reserves.
7. Follow the guidelines of international organizations like W.W.F. and UNESCO for forest conservation.

Question 2.
Write the uses of forests?
Answer:
Forests are useful to us for the following reasons:

1. Forests provide timber for building and furniture.
2. Forests keep the environment cool and increase the chances of rainfall.
3. The roots of the trees hold the soil firmly thereby checking soil erosion.
4. Forests provide habitat to a variety of wild plants and animals.
5. The plants of forests use CO₂ and release oxygen in photosynthesis, thereby maintaining balance of gases in atmosphere.
6. Forests provide animal products such as honey, lac, wax, etc.
7. Forests provide plant products such as fruits, nuts, gums, resins, fibres, medicines, essential oil (like sandal wood), etc.
8. They are involved in the absorption of water which percolates in the soil, thereby becoming a part of the groundwater.

Question 3.
What will happen if forests disappear?
Answer:

1. Soil erosion will increase which will affect soil fertility and productivity.
2. Air pollution will increase which will ultimately threaten thirty existence of life on the Earth.
3. Unpredictable changes will take place in weather and climate.
4. Reduction in rainfall.
5. Reduction in recharging of existing water resources
6. Wildlife may also disappear along with forest.
7. Shortage of forest products.
8. Disturbance in ecological balance.
9. Increase in temperature
10. Global warming may reach in flooding of low lying area.

Question 4.
Draw a figure to show the difference between canopy and under stories?
Answer:

Question 5.
Draw a figure to show in the dependence of plant, soil and decomposers in a forest?
Answer:

MP Board Class 7th Science Solutions

MP Board Class 7th General English Paragraph Writing

एक ही विषय पर या उससे सम्बन्धित विषय पर कहे गये वाक्यों के समूह को गद्यांश कहते हैं।

गद्यांश लेखन के नियम –

1. प्रत्येक गद्यांश एक ही विषय से सम्बन्धित होना चाहिए एवं उसका प्रत्येक वाक्य मुख्य विषय से सम्बन्धित होना चाहिए।
2. गद्यांश का प्रथम वाक्य पाठक की उत्सुकता जगाने वाला व अन्तिम वाक्य उसकी जिज्ञासा शान्त करने वाला होना चाहिए।
3. गद्यांश में विचारों या घटनाओं का क्रम उनके घटित होने के क्रम में व मुख्य विषय से सम्बन्धित होना चाहिए।

Question 1.
Write about your experience of journey by train/bus/aeroplane/ship in a paragraph.
Answer:
Experience of a journey by train
In the journey by train, we travel with the people who speak different languages, wear different dresses and eat different things. There is great rush in the compartment. There is dirt all around. Pure water is not supplied. Mostly, people cover their journey without having any seat. There is no light. The train journey is not comfortable.

कठिन शब्द:
journey – यात्रा
different – अलग-अलग
supplied – प्रदान करना
comfortable – आरामदायक।

Question 2.
Write a paragraph about things you like most in life (people, places, things) and how you spend time with them.
Answer:
I like the hilly areas where I am able to remain in the midst of the nature. Trees give fresh air and make the atmosphere peaceful. Birds sing their songs and remove the heaviness of the mind. Flowing water of a small river or fountain inspires to move onward and makes my heart pure. This is how I spend my time in Chitrakut.

कठिन शब्द:
midstata – बीच में
fresh – ताजा
atmosphere – वातावरण
peaceful – शान्त
heaviness – भारीपन
flowing – बहता हुआ
fountain – झरना
inspire – प्रेरित करना।

Question 3.
Write a paragraph on your grandfather.
Answer:
My Grandfather

My Grandfather is a farmer. He has a good experience of farming. He is 75 years of age. He still works hard. He reads book without spectacles. He is tall and wears dhoti and kurta. He goes to his fields in the morning and watches the work done by the workers.

कठिन शब्द:
experience – अनुभव
work hard – मेहनत करना
spectacles – चश्मा
fields – खेत
watch – देखना

Question 4.
Write a paragraph on your favourite tree.
Answer:
Mango Tree or My Favourite Tree

Mango tree is my favourite. It is found all over India. It grows and develops very large. It bears fruits. In rains its juice becomes very sweet. Its raw fruits are used in making pickles, chutnies and jam also. Ripe mango gives us juice. Its leaves look beautiful and are used to decorate the doors of the houses when some religious duty is being made. It bears fruits in the months from May to August.

कठिन शब्द:
grows – उगता है
develops – विकसित हो जाता है
large – विशाल
bears fruits – फल लगते हैं
juice – रस
raw – कच्चे
pickles – अचार
jam – मुरब्बा
ripe mango – पके आम
decorate – सजाना
religious duty – धार्मिक कार्य

MP Board Class 7th English Solutions

MP Board Class 7th Science Solutions Chapter 15 Light

Light Intex Questions

Question 1.
Paheli wants to know, what makes things visible to us? Boojho thinks that objects are visible only when light reflected from them reaches our eyes. Do you agree with him?
Answer:
Yes.

Question 2.
Boojho noted in his notebook: Is it not surprising that my image is of the same size as me whether the mirror is small or large?
Answer:
Yes.

Question 3.
Paheli made a note in her notebook: In a plane mirror the image is formed behind the mirror. It is erect, of the same size and is at the same distance from the mirror as the object is in front of it?
Answer:
Yes.

Question 4.
Boojho saw an ambulance on the road. He was surprised to see that the word ‘AMBULANCE’ in front was written in a strange manner?
Answer:
When the driver of a vehicle ahead of an ambulance looks in her/his rear view mirror, he/she can read ‘AMBULANCE’ written on it and give way to it. It is the duty of every one of us to allow an ambulance to pass without blocking its way.

Activities

Activity – 1
Write down the letters ABC on a piece of paper with sketch pen and look at its image in a plane mirror. Then find out which letters look the same as on the paper and which letters look different (fig.) Try to write these letters as seen in the mirror
Answer:

Activity – 2
Take a red book and allow white light to fall on it (fig)
Answer:
The color of the book is due to the red color which gets reflected from the book, i.e., it reflects only red color while it absorbs all the other colours of white light. A rose is red because it reflects only red light.

Light Text Book Exercises

Question 1.
Fill in the blanks:

1. An image that cannot be obtained on a screen is called ………………………..
2. Image formed by a convex ……………………….. is always virtual and smaller in size.
3. An image formed by a …………………….. mirror is always of the same size as that of the object.
4. An image which can be obtained on a screen is called a ………………………….. image.
5. An image formed by a concave ………………………. cannot be obtained on a screen.

Answer:

1. Virtual image
2. Mirror
3. Plane
4. Real
5. Lens

Question 3.
Match the items given in of Column I with one or more items Column II:

Answer:

1. (a) – (v)
2. (b) – (ii)
3. (c) – (i)
4. (d) – (iii)
5. (e) – (vi)

Question 4.
State the characteristics of the image formed by a plane mirror?
Answer:
The characteristics of the image formed by a plane mirror are:

1. It forms an erect image.
2. It forms a virtual image.
3. It forms the image behind the mirror.
4. The size of the image is same as that of the object.
5. It forms the image at the same distance behind the mirror as the object stands infront of it.

Question 5.
Find out the letters of English alphabet or any other language known to you in which the image formed in a plane mirror appears exactly like the letter itself. Discuss your findings?
Answer:
Letters like A, H, I, M, O, T, U, V, and W.

Question 6.
What is a virtual image? Give one situation where a virtual image is formed?
Answer:
The image which cannot be taken on a screen is called a virtual image. For example, when some object is placed very close to the concave mirror we do not get any image of that object on the white screen placed behind the mirror. This type of image is known as virtual image.

Question 7.
State two differences between a convex and a concave lens?
Answer:
Convex lens:

1. These are thick at middle and thin at edge.
2. They can form magnified image.

Concave lens:

1. These are thin at middle and thick at edge.
2. The image formed by these lens are always diminished in size.

Question 8.
Give one use each of a concave and convex mirror?
Answer:
Use of convex mirror:
It is used in vehicles as rear view mirror.

Concave mirror:
It is used by dentists to examine is used in vehicles as rear view mirror.

Question 9.
Which type of mirror can form a real image?
Answer:
Concave mirror.

Question 10.
Which type of lens forms always a virtual image?
Answer:
Concave lens.

Choose the correct option in questions 11 – 13:

Question 11.
A virtual image larger than the object can be produced by a –

1. Concave lens
2. Concave mirror
3. Convex mirror
4. Plane mirror

Answer:
2. concave mirror

Question 12.
David is observing his image in a plane mirror. The distance between the mirror and his image is 4 m. If he moves 1 m towards the mirror, then the distance between David and his image will be –

1. 3 m
2. 5 m
3. 6 m
4. 8 m.

Answer:
3. 6 m

Question 13.
The rear view mirror of a car is a plane mirror. A driver is reversing his car at a speed of 2 m/s. The driver sees in his rear view mirror the image of a truck parked behind his car. The speed at which the image of the truck appears to approach the driver will be –

1. 1 m/s
2. 2 m/s
3. 4 m/s
4. 8 m/s.

Answer:
3. 4 m/s

Extended Learning – Activities and Projects

Question 1.
Play with mirror? Write your name with a sketch pen on a thin sheet of paper, polythene or glass. Read your name on the sheet while standing infront of a plane mirror. Now look at your image in the mirror?
Answer:
Do yourself

Question 2.
A burning candle in water? Take a shoe box, open on one side. Place a small lighted candle in it. Place a clear glass sheet Fig- Candle burning in water (roughly 25 cm x 25 cm) infront of this candle (Fig.). Try to locate the image of the candle behind the glass sheet. Place a glass of water at its position. Ask your friends to look at the image of the candle through the sheet of glass. Ensure that candle is not visible to your friends. Your friends will be surprised to see the candle burning in water. Try to explain the reason?
Answer:
Do yourself.

Question 3.
Make a rainbow?
Try to make your own rainbow. You can try this project in the morning or in the evening. Stand with your back towards the sun/ Take a hosepipe or a water pipe used in the garden. Make a fine spray in front of you. You can see different colours of rainbow in the spray?
Answer:
Do yourself.

Question 4.
Visit a laughing gallery in some science centre or a science park or a village mela. You will find some large mirrors there. You can see your distorted and funny images in these mirrors. Try to find out the kind of mirrors used there?
Answer:
Do yourself.

Question 5.
Visit a nearby hospital. You can also visit the clinic of an ENT specialist, or a dentist. Request the doctor to show you the mirrors used for examining ear, nose, throat and teeth. Can you recognise the kind of mirror used in these instruments?
Answer:
Do yourself.

Question 6.
Role play?
Here is a game that a group of children can play. One child will be chosen to act as object and another will act as the image of the object. The object and the image will sit opposite to each other. The object will make movements, such as raising a hand touching an ear, etc. The image will have to make the correct movement following the movement of the object. The rest of the group will watch the movements of the image. If the image fails to make the correct movement, she/he will be retired. Another child will take her/his place and the game will continue. A scoring scheme can be introduced. The group that scores the maximum will be declared the winner?
Answer:
Do yourself.

Light Additional Important Questions

Objective Type Questions

Question 1.
Choose the correct alternative:

Question (a)
Formation of shadows suggests that light travels in –
(a) vacuum
(b) straight lines
(c) dark rooms
(d) None of these.
Answer:
(b) straight lines

Question (b)
A smooth polished surface which can return back the rays of light into the same medium is called –
(a) mirror
(b) lens
(c) prison
(d) None of these.
Answer:
(a) mirror

Question (c )
The phenomenon of bouncing back of the rays of light into the same medium is called –
(a) reflection
(b) refraction
(c) scattering
(d) None of these.
Answer:
(a) reflection

Question (d)
If the image cannot be taken on the screen, it must be –
(a) real
(b) virtual
(c) real or virtual
(d) None of these.
Answer:
(b) virtual

Question (e)
A spherical mirror with its reflecting surface on the outside is a –
(a) plane mirror
(b) convex mirror
(c) concave mirror
(d) None of these.
Answer:
(b) convex mirror

Question (f)
The mirror which is used as rear – view mirror in cars and scooters is, by nature –
(a) plane
(b) convex
(c) concave
(d) None of these.
Answer:
(b) convex

Question (g)
An image that can be obtained on a screen is –
(a) virtual
(b) real
(c) both real and virtual
(d) None of these.
Answer:
(b) real

Question (h)
The image produced by a plane mirror is –
(a) small
(b) real
(c) inverted
(d) equal size virtual and erect.
Answer:
(d) equal size virtual and erect.

Question (i)
In the formation of rainbow the altitude of the sun should be between or less than –
(a) 40° to 42°
(b) 42° to 44°
(c) 41° to 43°
(d) 0° to 40°.
Answer:
(a) 40° to 42°

Question (j)
White light comprises of ……………………… colours?
(a) 7
(b) 5
(c) 3
(d) 8.
Answer:
(a) 7

Question (k)
Which of the following can be used to prove that light consists of seven colours?
(a) plane mirror
(b) convex lens
(c) Newton’s disc
(d) None of these.
Answer:
(c) Newton’s disc

Question (l)
If the speed of rotation of Newton’s colour disc is fast enough, the various colours would blend and produce –
(a) white light
(b) red light
(c) no light at all
(d) green light.
Answer:
(a) white light

Question (m)
Primary colours are –
(a) red, blue, yellow
(b) red, yellow, magenta
(c) red, blue, green
(d) None of these.
Answer:
(c) red, blue, green

Question (n)
Which color is produced by mixing of blue and green?
(a) cyan
(b) magenta
(c) yellow
(d) blue.
Answer:
(a) cyan

Question 2.
Fill in the blanks:

1. The surface of water can act like a mirror and change the path of …………………………
2. An image formed by a plane mirror is erect and of the same size as the ……………………
3. The curved shining surface of a spoon acts as a ……………………
4. The inner surface of the cut ball is called and the outer surface is called ………………………
5. Concave mirrors are also used by dentists to see an enlarged image of the ………………………
6. The reflectors of tourches, headlights of cars and scooters are ……………………….. in shape.
7. The magnifying glass is actually a type of a ……………………………..
8. A convex lens is also called ………………………….. lens.
9. A concave lens is also called ……………………….. lens.
10. The rainbow has ………………………… colours.
11. The process of splitting up of white light into different colours is called ……………………
12. In a common rainbow the …………………………. colour is observed in the inner fringe and ………………………. on the outer fringe.

Answer:

1. Light
2. Object
3. Mirror
4. Concave, convex
5. Teeth
6. Concave
7. Lens
8. Converging
9. Diverging
10. Seven
11. Dispersion of light
12. Violet, red.

Question 3.
Which of the following statements are true (T) or false (F):

1. A shining stainless steel’spoon or plate can change the direction of light.
2. In a plane mirror only sides are interchanged.
3. The common example of a curved mirror is a spherical mirror.
4. The reflecting surface of the bell is convex.
5. Convex mirrors can form images of objects spread over a large area.
6. The lenses are not transparent.
7. A concave lens always forms erect, virtual and smaller image than the object.
8. A rainbow is seen as a large arc in the sky with many colours.
9. The sunlight consists of five colours.
10. The white light is composed of seven colours.

Answer:

1. True
2. Ture
3. True
4. True
5. True
6. False
7. True
8. True
9. False
10. True

Light Very Short Answer Type Questions

Question 1.
Give the names of four different sources of light?
Answer:
The four different sources of light are:

1. Sun
2. Stars
3. Moon
4. Firefly.

Question 2.
How does light travel from one point to the other?
Answer:
Light travel from one point to the other in straight line.

Question 3.
How can we change the direction of the light?
Answer:
We can change the direction of light by the phenomenon called reflection.

Question 4.
What is refraction?
Answer:
Bending of light when it travels from one medium to another is called refraction.

Question 5.
Define concave mirror?
Answer:
In a spherical mirror, of the reflecting surface is on the inside, it is called a concave mirror.

Question 6.
Define convex mirror?
Answer:
In a spherical mirror, if the reflecting surface is on the outside, it is called a convex mirror.

Question 7.
Define reflection of light?
Answer:
The phenomenon of turning back of light into the same medium on striking a polished surface is called reflection of light.

Question 8.
Define real image?
Answer:
An image that can be captured on a screen is called a real image.

Question 9.
Define virtual image?
Answer:
An image which cannot be captured on a screen is called a virtual image.

Question 10.
Define plane mirror?
Answer:
A plane polished surface capable of reflecting light regularly is known as a plane mirror.

Question 11.
How is the word AMBULANCE written on an ambulance?
Answer:

Question 12.
What happens when light falls on a mirror?
Answer:
The mirror reflects the direction of light that falls on it.

Question 13.
Why is the sky blue?
Answer:
The blue color of the sky is the result of the white light from the sun being separated into different colours.

Question 14.
Where do the different colours come from?
Answer:
All Colours came from light.

Question 15.
Define dispersion?
Answer:
The branching of white light into various colours is called dispersion of light.

Question 16.
How rainbows are formed?
Answer:
Rainbows are formed by sunlight falling on rain drops.

Question 17.
Have you ever seen a rainbow in the sky?
Answer:
Yes.

Question 18.
Does the white light consists of seven colours?
Answer:
Yes.

Light Short Answer Type Questions

Question 1.
Name the four features of the image formed by a plane mirror?
Answer:
The four features of the image formed by a plane mirror are:

1. The image formed by a plane mirror is as far behind the mirror as the object is in front of it.
2. It is virtual.
3. It is exactly of the same size and shape.
4. It is erect but laterally inverted.

Question 2.
What is the real image of an object?
Answer:
Real image is that image where the rays of light actually pass hence, it can be taken on the screen and is always inverted.
For example: image formed by pinhole camera, convex lens and concave mirror etc.

Question 3.
Name two situations in which the real image of an object is formed?
Answer:

1. When the object is at infinity.
2. When the object is at centre of curvature.

Question 4.
Give one use each Of concave and convex mirrors?
Answer:
Use of concave mirror:

1. They are used in reflected of car, head-lights and search lights.
2. They are used as shaving mirrors.
3. They are used in telescopes.

Use of convex mirrors:

1. They are used in automobiles by the drivers for seeing the erect images of the traffic.

Question 5.
What is virtual image? Give one example of virtual image?
Answer:
Virtual image is that image where the rays of light appear to intersect hence, it can only be seen, but it cannot be taken on the screen and is always erect. For example, image formed by plane mirror convex mirror and concave lens etc.

Question 6.
State two uses of concave mirror?
Answer:
The two uses of concave mirror are :

1. Concave mirrors are used as reflectors in car head-lights, search lights, torches and table lamps.
2. Concave mirrors are used by doctors to concentrate light on nose, ear, eyes etc.

Question 7.
Mention some of the uses of plane mirror?
Answer:
Uses of plane mirror are:

1. In hair cutting saloons, shops and at home.
2. For constructing periscope.
3. For constructing kelodoscope.

Question 8.
How will you come to know that the mirror given to you is a concave or convex?
Answer:
In the concave surface the polish is done on its outer surface and the inner surface is shining. If we bring it closer to our face the later will look very big. In a convex mirror the polish is done on the inner surface and then outer side is shining. In this mirror our face will always appear to be shorter.

Question 9.
Draw a ray diagram to explain the formation of a virtual image of a point source of light in a plane mirror?
Answer:
The image of a point object formed by a plane mirror.

Question 10.
In figure, complete the image of the coin after reflection at the surfaces of both the mirrors?

Fig. A ray diagram for formation of image by a pair of inclined mirrors.

Question 11.
Differentiate between real and virtual image formed by mirrors?
Answer:
Difference between real and virtual image:
Real image:

1. It can be obtained on a screen.
2. It is inverted.
3. It is obtained on the same side of mirror as the object.
4. Rays converge at a point to form the image.

Virtual image:

1. It cannot be obtained on a screen.
2. It is erect.
3. It is formed always behind the mirror.
4. Rays appear to diverge from a point where the image is formed.

Question 12.
Draw concave and convex mirrors?
Answer:

Question 13.
Draw convex and concave lens?
Answer:

Question 14.
Differentiate between reflection and refraction?
Answer:
Differences between reflection and refraction:
Reflection:

1. The speed of light remains the same.
2. The incident ray and the reflected ray travel in the same media.
3. In reflection the ray of light gets reflected back into the same medium.

Refraction:

1. The speed of light varies as it travels from one medium to another.
2. The incident ray and the refracted ray travel in different media.
3. In the refraction the ray of light bends at the surface of separation between the two media.

Question 15.
Define mixing of colours? What is the color of the object as the red and green glasses?
Answer:
When two colours mix or overlap, a third color is produced. Thus, red + green = yellow; red + blue = magenta; red + blue + green = white and so on. In fact, any color can be obtained by the combination of red, green and blue which are called the primary colours. The colours so produced. From them are called secondary colours. The mixing of colours can be shown with the help of the diagram given in fig.

Light Long Answer Type Questions

Question 1.
Explain the image formation in plane mirror?
Answer:
A mirror with a plane surface is called a plane mirror. The ordinary mirror we use is a plane mirror. Formation of image is one of effects on reflection of light. The image is seen behind the mirror and it is of the same size as the object. The distance from the object to the mirror and the distance between the mirror and the image are equal. In the plane mirror the right side of the object appears to be left side of the image, and the left side of the object appears to be the right side of the image. This inversion of sides is known as lateral inversion.

Question 2.
Define Newton’s experiment?
Answer:
Newton’s Experiment:
The idea that sunlight consists of several colours was first put forward by Sir Isaac Newton. He passed a narrow beam of light into a prism. The light that emerged from the prism was found to be coloured as in a rainbow. He gave the name spectrum to this coloured patch of light. The spectrum was seen to consist of seven colours of light – violet, indigo, blue, green, yellow, orange and red. The various colours found in white light can be easily remembered as VIBGYOR. The process of splitting up of white light into different colours is called dispersion of light.

Question 3.
Explain rainbow?
Answer:
Rainbows are formed by sunlight falling on rain drops. The rainbow is always observed with the back towards the sun. The rainbow is formed when rain drops owing to refraction and internal reflection produce deviation and dispersion into seven colours of the sunlight falling on them. The rainbows are visible only when the altitude of the sun is less than 42°.

A full rainbow can be seen from an aeroplane flying at higher altitudes. It is a matter of common observation that when one looks at a spray of water on which sun shines, rainbows are seen. When you look at the water falls with the sun shining at your back, a circular rainbow will be seen. In a common rainbow (primary rainbow) the violet color is observed in the inner fringe and red on the outer fringe.

Question 4.
How will you show that combining seven colours, we get white light?
Answer:
Take a circular cardboard disc of about 10 cm diameter. Divide this disc into seven segments. Paint the seven rainbow colours on these segments as shown in Fig. (a). A small hole is made at the center of the disc. Fix the disc loosely on the tip of a refill of a ball pen. Ensure that the disc rotates freely [Fig.(a)]. Rotate the disc in the daylight. When the disc is rotated fast, the colours get mixed together and the disc appears to be whitish [Fig. (b)]. This disc is popularly known as Newton’s disc.

MP Board Class 7th Science Solutions

MP Board Class 7th General English Grammar

Artticle (आर्टिकल)
उपपद

Article तीन हैं – (1) a, (2) an,(3) the.
a तथा an का प्रयोग एकवचन के लिए होता है। the का प्रयोग एकवचन तथा बहुवचन दोनों के लिए होता है।
(1) A का प्रयोग – Consonant (व्यंजन) से प्रारम्भ होने वाले एकवचन की जातिवाचक संज्ञा के पूर्व होता है। जैसे-a book, a man, a dog, a cat आदि।
(2) An का प्रयोग – vowels (a, e, i, 0, u) स्वर से प्रारम्भ होने वाले एकवचन की जातिवाचक संज्ञा के पूर्व होता है।
जैसे – An apple, an eye, an inkpot, an orange, an umbrella आदि।
(3) The का प्रयोग-किसी खास वस्तु, अनोखी वस्तु, नदी, पहाड़, प्रसिद्ध ग्रन्थ, अखबार के नाम आदि के पहले होता है। जैसे-The sun, The earth, The Ganga, The Indian Ocean, The Taj, The East आदि। किसी खास या पूर्व परिचित वस्तु का बोध कराने के लिए भी The का प्रयोग किया जाता है। जैसे-The girl in blue is my sister.

Exercise

Fill in the following blanks with a, an or the as required

1. ……….. train was ………. hour late.
2. Srilanka is ………. island.
3. He is ……….. honest man.
4. It is ………… large egg.
5. ……….. umbrella is ……. use full thing.
6. ………… rose is ………. loveliest of all flowers.
7. He is ……… M. A. from Allahabad university.
8. …… Gita is ………. holy book of Hindus.

Answer:

1. The, an
2. an
3. an
4. a
5. An, a
6. The, the
7. an
8. Thea, the.

The Pronoun (द प्रोनाऊन)
सर्वनाम

Pronoun वह शब्द है जिसका प्रयोग संज्ञा (Noun) के स्थान पर होता है। जैसे –
Hari is my friend. He lives in Delhi.
यहाँ He, सर्वनाम (Pronoun) है। यह Noun-Hari के स्थान पर आया है।

Kinds of Pronoun (सर्वनाम के प्रकार)

1. Personal Pronouns (पुरुषवाचक सर्वनाम)
उदाहरण – I, We, You, He, She, It, They, Me, Us, Him, Her, Them, Mine, Ours, Yours आदि।

2. Reflexive Pronouns (निजवाचक सर्वनाम)
उदाहरण – Myself, yourself, himself, herself, ourselves, themselves.

3. Demonstrative Pronouns (संकेतवाचक सर्वनाम)
उदाहरण – this, that, these, those.

4. Interrogative Pronouns (प्रश्नवाचक सर्वनाम)
उदाहरण – Who, which, whom, whose, what.

5. Relative pronouns (सम्बन्धवाचक सर्वनाम)
उदाहरण – Who, Whom, Whose, Which, That, What, आदि।

6. Indefinite Pronouns (अनिश्चयवाचक सर्वनाम)
उदाहरण – anybody, somebody, nobody, someone, one, none, all, mony, few.

7. Distributive Pronouns (प्रत्येकवाच सर्वनाम)
उदाहरण – each, either, neither.

8. Reciprocal Pronouns (पारस्परिक सर्वनाम)
ये दो pronouns से मिलकर बनते हैं और केवल दो हैं – each other, one another.

9. Possessive Pronouns (अधिकार वाचक सर्वनाम)
उदाहरण – mine, yours, hers. आदि।

Exercise

Pick out the pronouns in the following sentences :
(निम्न वाक्यों में से सर्वनाम छाँटिए।)

1. I know him very well.
2. She has a pretty doll.
3. They are playing cricket.
4. I shall beat you.
5. The boy who made a noise was punished.
6. The man whose bag was stolen has come.
7. Where is the pen which I gave you.
8. Why do you abuse one another ?
9. These are nice girls.
10. They decided to help each other.

Noun (नाऊन)
संज्ञा

Countable and uncountable
संज्ञाओं (Nouns) को उनके गिने जाने के आधार पर दो प्रकार में बाँटा गया है –

(1) Countable Nouns – (गिने जाने योग्य संज्ञाएँ)
जैसे-dog, pen, country, table, road आदि।

(2) Uncountable Nouns – (नहीं गिने जाने योग्य संज्ञाएँ)
जैसे – butter, juice, sugar, hatred, love, sickness. आदि।

The Adverb (एडवर्व)
क्रिया-विशेषण

Adverb (क्रिया विशेषण) वह शब्द है जो किसी Verb (क्रिया), Adjective (विशेषण) या Adverb (क्रिया-विशेषण) की विशेषता बताता है। जैसे

The milk is very hot. Sarita ran fast but could not win the race.
उपरोक्त वाक्यों में very और fast क्रिया-विशेषण हैं।

Kinds of Adverbs

(1) Adverbs of Time (काल-वाचक)
उदाहरण-now, always, never, already, shortly, today, tomorrow आदि।

(2) Adverbs of Place (स्थान-वाचक)
उदाहरण-here, there, in, below, hence, thence, inside आदि।

(3) Adverbs of Manner (रीति वाचक)
उदाहरण-quickly, fast, well, easily, bravely आदि।

(4) Interrogative Adverbs (प्रश्नवाचक)
उदाहरण-when, where, how, why, how much आदि।

(5) Relative Adverbs (सम्बन्ध वाचक)
उदाहरण-when, where, how, why आदि।

(6) Adverbs of Degree (परिणामवाचक)
उदाहरण-very, much, quite, wholly, exactly आदि।

(7) Adverbs of Affirmation and Negation (स्वीकार वाचक एवं निषेध वाचक)
उदाहरण-yes, no, not, certainly, indeed आदि।

(8) Adverbs of Number (संख्या वाचक)
उदाहरण-once, twice, first, again आदि।

(9) Adverbs of Reason (हेतु वाचक)
उदाहरण-therefore, so, hence.

Exercise

Pick out the adverbs in the following sentences :
(निम्नलिखित वाक्यों में से क्रिया-विशेषण छाँटिए)

1. The soldiers fought bravely.
2. You can stay here.
3. He went far into the forest.
4. Tell me quickly as you can.
5. Do you know why he came here ?
6. Have you ever been to Mathura ?
7. Why do you not work carefully ?
8. Come inside.
9. This shirt is too loose for me.
10. I went there only once.

Voice (वाइस)
वाच्य

Voice (वाच्य) क्रिया का वह रूप है जो यह बताता है कि subject (कर्ता) कार्य का करने वाला है या उसके प्रति कोई कार्य किया गया है।
Voice दो प्रकार के होते हैं –

(1) Active Voice और Passive Voice
जैसे – The hunter killed a lion-Active
शिकारी ने शेर को मार डाला।
The lion was killed by the hunter-Passive
शेर शिकारी के द्वारा मार डाला गया।

यहाँ, पहले वाक्य में कर्ता (subject) hunter कार्य करने वाला है इसीलिये verb “killed” Active voice में होगा। जबकि दूसरे वाक्य में subject lion’ के प्रति कार्य हो रहा है इसीलिये verb ‘was killed’ passive voice में होगा।

Active से Passive बनाना

(1)Active से Passive में बदलने के लिए ‘to be’ क्रियाओं का प्रयोग किया जाता है। सबसे पहले Object (कर्म) को Subject (कर्ता) के स्थान पर रखते हैं। इसके पश्चात् tense के अनुसार क्रिया ‘to be’ को फिर मुख्य क्रिया (verb) की 3rd form को रखते हैं और अन्त में कार्य करने वाले (doer) को शब्द by के बाद रखते हैं।

‘To be’ क्रियाएँ आठ हैं। बिना इनके passive नहीं बन सकता है।
Verb to be’.- is, are, am, was, were, be, been,being.
केवल transitive verb को passive voice में बदलते हैं क्योंकि उसका object होता है।

निम्न वाक्यों को पढ़ें –

Active – We like mangoes.
Passive – Mangoes are liked by us.
Active – The dog cought the rat.
Passive – The rat was cought by the dog.
Aetive – He is flying a kite.
Passive – A kite is being flown by him.

कभी-कभी कुछ nouns के दो objects होते हैं। Passive Voice में उनमे से किसी को भी Subject बनाया जा सकता है परन्तु अधिकतर Indirect Object को Subject की तरह प्रयोग करते हैं।

उदाहरण –
Active – He gave me a book.
Passive – I was given a book by him.
Or
A book was given (to) me by him.
Active – Ram told me stories at night.
Passive – I am told stories at night by Ram.
Or
Stories are told me at night by Ram.

Change of Tense (काल में परिवर्तन)

Exercise

Change the following sentences into Passive Voice :

1. The teacher teaches us English.
2. The peon rings the bell.
3. The Police arrested the thief.
4. The servent had beaten Ram.
5. The carpenter was making a table.
6. They had finished the work before the teacher came.
7. Our team will win the match.
8. The postman will help us.
9. He will visit me tomorrow.
10. Have you broken the cup ?

The preposition (द प्रिपोजिशन)
सम्बन्धसूचक अव्यय

परिभाषा – वे शब्द जो किसी Noun या Pronoun से पूर्व प्रयोग में आये हों और उनका सम्बन्ध वाक्य के किसी अन्य Noun या Pronoun के साथ स्थापित हो, Prepositions कहलाते हैं।
A preposition is a word placed before a noun or a pronoun to show the relation of the person or thing denoted by it.

Relations expressed by Prepositions

1. Preposition of Time – कुछ Prepositions समय सूचक होते हैं, जैसे-

1. He came at seven.
2. I study for seven hours daily.
3. She is absent from class for five days.

2. Preposition of Place – कुछ Prepositions स्थान सूचक होते है, जैसे-

1. He was in his room.
2. They are coming home from the school.
3. I stood before him.

3. Prepositions of Movement – Prepositions गतिसूचक/साधन सूचक होते हैं, जैसे-

1. I travelled by train.
2. I came by car.
3. We went there on his bike.

Use of some other Prepositions

1. At, In – At छोटे स्थान के साथ प्रयोग किया जाता है
In बड़े स्थान के साथ प्रयोग किया जाता है। जैसे –
(i) He lives at Bhopal.
(ii) We live in India.

2. In, into – In स्थिति को बताता है और Into गति का बोध करता है। जैसे –
(i) All the boys are in the classroom.
(ii) We bought the tickets and went into the hall.

3. With, by – With यन्त्र के साथ प्रयोग होता है और by कार्य करने वाले के साथ प्रयोग किया जाता है। जैसे –
(i) We cut the apple with the knife.
(ii) The snake was killed by the farmer.

4. Since, for-Since निश्चित समय के साथ (जैसे दिन का नाम या तिथि आदि) और For समय की अवधि के साथ प्रयोग किया जाता है। जैसे –
(i) He has been ill since Wednesday.
(ii) Raj has been absent for three days.

5. Between, among-Between दो व्यक्तियों तथा Among दो से अधिक व्यक्तियों के लिए प्रयोग किया जाता है। जैसे-
(i) Divide these mangoes between Ram and Ravi.
(ii) The gentleman divided his property among his four sons.

6. On, upon-On गतिहीनता तथा Upon गतिशीलता के लिए प्रयोग किया जाता है। जैसे –
(i) The cat is sitting on the table.
(ii) The dog sprang upon the table.

7. In, within-In समय की अवधि की समाप्ति का बोध कराता है और Within समय की अवधि के भीतर का बोध कराता है। जैसे –
(i) I shall come back in a week. (एक सप्ताह की समाप्ति पर।)
(ii) I shall come within a week. (एक सप्ताह समाप्त होने से पूर्व।)

8. Below, beneath-Below पद के सन्दर्भ में और Beneath स्थान के सन्दर्भ में प्रयोग किया जाता है। जैसे –
(i) Your brother is below my rank.
(ii) The lion sat beneath a tree.

9. Beside, besides-Beside का अर्थ है-पास (by the side of) जबकि Besides का अर्थ है-अतिरिक्त जैसे –
(i) The boys stood beside the teacher’s chair.
(ii) Besides the principal other teachers spoke in the prayer assembly.

10. With, without-With का अर्थ है-साथ और without का अर्थ-बिना (रहित)। जैसे –
(i) Come to me with your brother.
(ii) Come to the field without anything.

Exercise

Fill in the blanks with the appropriate prepositions :

1. She is looking ……….. a job. (to, for)
2. I have invited him ……… dinner. (to, for)
3. Your sister is angry ……… you. (with, from)
4. Your letter is full ……….. mistakes. (of, by)
5. I met him ………. chance. (by, in)
6. They came here …….. Monday.(on, at, since)
7. She prefers tea ………. coffee. (to, thanong)
8. Distribute these sweets ………. the children. (between, an jong)
9. The frog jumped ………. the pond. (in, into)
10. The book is ………. the table. (on, in, over)

Answer:

1. For
2. to
3. with
4. of
5. by
6. on
7. to
8. among
9. into
10. on.

Direct and Indirect Narration
(डाइरेक्ट एण्ड इन्डाइरेक्ट नरेशन)

Direct Narration में बोलने वाले के कथन को ज्यों का त्यों ही दोहरा दिया जाता है। परन्तु Indirect Narration में उस कथन का भाव प्रकट किया जाता है।
जैसे-He said to me, “I weep to see you.” (Direct)
He told me that he wept to see me. (Indirect)

निर्देश :
(1) Said को Told में बदल देते हैं। Inverted Commas को हटा देते हैं तथा Persons में परिवर्तन निम्नलिखित रूप में करते हैं।

(2) Ist Person के Pronoun (I, we, us, our) का परिवर्तन Direct speech के Subject (कर्ता) के Person के अनुसार होता है। IInd Person के Pronoun (you, your) का परिवर्तन Object के Person के अनुसार होता है तथा IIIrd person के Pronoun में कोई भी परिवर्तन नहीं होता है।

(3) निकटता प्रकट करने वाले शब्दों में परिवर्तन निम्नलिखित रूप से किया जाता है –

(4) Tense (काल) में परिवर्तन – (1) Reporting Verb के Present या Future Tense में होने पर Reported Verb के Tense में कोई परिवर्तन नहीं होता है। (2) Reporting Verb के Past Tense में होने पर
Reported Verb के Tense में परिवर्तन होता है –
(i) Simple present का Simple past हो जाता है –
Direct – He said, “She works hard.”
Indirect – He said that she worked hard.

(ii) Present Continuous का Past Continuous हो जाता है –
Direct-He said, “She is reading a book.”
Indirect-He said that she was reading a book.

(iii) Present perfect का Past perfect हो जाता है-
Direct-He said, “She has done her work.”
Indirect-He said that she had done her work.

(iv) Present Perfect Continuous का Past Perfect Continuous हो जाता है-
Direct-He said, “She has been reading a book for two hours.”
Indirect-He said that she had been reading a book for two hours.

(v) Simple past का Past Perfect हो जाता है-
Direct-He said, “She wrote a letter.”
Indirect-He said that she had written a letter.

(vi) Past Continuous का Past Perfect Continuous हो जाता है-
Direct-He said, “She was writing a letter.”
Indirect-He said that she had been writing a letter.
Shall का should, may का might, can का could हो जाता है तथा सदा सत्य और ऐतिहासिक तथ्यों का Tense नहीं बदला जाता।

Interrogative (Questions)

Direct-Rahul said to Rama, “Is it easy to ride a bicycle ?”
Indirect-Rahul asked Rama if it was easy to ride a bicycle.
Direct-The bird said to the Prince, “Why are you weeping ?”
Indirect-The bird asked the Prince why he was weeping.

Command and Orders

Direct-“Get some sleep”, his father said.
Indirect-His father told him to get some sleep.
Direct-“Don’t stay up late,” his mother said.
Indirect-His mother told him not to stay up late.
Direct-“Please help me,” Hari said to me.
Indirect-Hari requested me to help him.

Exercise

Rewrite the following sentences in indirect form of narration :

1. The farmer said, “The rain is useful for crops.”
2. Ram said to sheela, “I am your brother.”
3. The teacher said, “The sun rises in the east.”
4. Akshay said, “Who is running on the roof ?”
5. His brother said to me, “Where do you go daily at this time?”
6. She said to you, “When do you go for a walk?”
7. Anu said to me, “From where have you bought this shawl ?”
8. Rohan said to the boy, “Why did you not take medicine ?”

Answers :

1. The farmer said that the rain is useful for crops.
2. Ram told Sheela that he was her brother.
3. The teacher said that the sun rises in the east.
4. Akshay asked who was running on the roof.
5. His brother asked me where did I go daily at that time.
6. She asked you when you went for a walk.
7. Anu asked me from where I had bought that shawl.
8. Rohan asked the boy why he had not taken medicine.

Degrees of Comparison
(डिग्रीज़ ऑफ कम्परिजन),

गुण या दोष की अधिकता या कमी बताने के लिए Adjective की तीन अवस्थाएँ होती हैं-
(1) Positive degree
(2) Comparative degree
(3) Superlative degree.

Exercise

Fill in the blanks with a suitable word given in brackets :

1. He is ………… than other boys in the class. (stronger, strong)
2. Sita is …………. than Gita. (rich, richer)
3. Ram is not as …………. as Shyam. (poor, poorer)
4. Of the three mangoes this is the …………. (sweet, sweetest)
5. Ravi is …………. than his brother. (clever, cleverer)
6. Iron is the …………. of all the metals. (hardest, harder)
7. She is not so …………. as her sister. (intelligent, more intelligent)
8. It is the ……….. among all books I have ever read. (good, better, best)

Answer:

1. stronger
2. richer
3. poor
4. sweetest
5. cleverer
6. hardest
7. intelligent
8. best.

Complex Sentences
(मिश्रित वाक्य)

Complex sentence में एक Principal Clause (प्रधान उपवाक्य) तथा शेष. Subordinate Clause होते हैं। इस तरह clause तीन प्रकार के होते हैं – (1) Principal Clause, (2) Subordinate Clause (आश्रित उपवाक्य) तथा (3) Co-ordinate clause (समानपदीय उपवाक्य)।

Subordinate Clause तीन प्रकार के होते हैं –
(1) Noun Clause
(2) Adjective Clause
(3) Adverb Clause.

Adjective Clause
(एडजेक्टिव क्लॉज़)

Adjective clause यदि एक वाक्य (sentence) में आये हुए Noun या Pronoun के लिए दूसरे वाक्य में कोई बात कही गई है तो दूसरे वाक्य को Adjective clause बना देते हैं।
जैसे –
1. I saw a cat. The cat was lying on the road.
Answer:
I saw a cat who was lying on the road.

2. I gave her a pencil. The pencil was very cheap.
Answer:
I gave her a pencil which was very cheap.

3. The girl is wearing a red sweater. She is Savita.
Answer:
The girl, who is wearing a red sweater, is Savita.

4. Arif is wearing a blue shirt. He is the tallest boy in the class.
Answer:
Arif, who is the tallest boy in the class, is wearing a blue shirt.

5. Seema is in class ten. She is going to play in the national team.
Answer:
Seema, who is going to play in the national team, is in class ten.

6. Mohan is a swimming champion. He is going to teach his friends to swim.
Answer:
Mohan, who is a swimming champion, is going to teach his friends to swim.

7. Asma helped the boy. He is blind.
Answer:
Asma helped the boy, who is blind.

Interrogative Sentences
(प्रश्नवाचक वाक्य)

निर्देश-Simple Positive वाक्यों को Interrogative बनाने के लिए सहायक क्रिया (Auxiliary verb), मुख्य क्रिया (Main verb) तथा प्रश्नवाचक शब्दों (Question words) की सहायता लेते हैं। जैसे-

(1) उसके पास नई कार है।
She has a new car. (Positive)
Has she a new car? (Interrogative)

(2) राम एक अच्छा लड़का है।
Ram is a good boy. (Simple)
Is Ram a good boy? (Interrogative)

Change the following sentences into Interrogative one :

1. मीनू शिमला जा रही है।
Meenu is going to Shimla.
Is Meenu going to Shimla ?

2. वह यहाँ आ सकता है।
He can come here.
Can he come here?

3. राम एक पत्र लिख चुका है।
Ram has written a letter.
Has Ram written a letter?

4. वह एक पत्र लिखती है।
She writes a letter
Does she write a letter ?

5. उसने एक गीत गाया।
She sang a song.
Did she sing a song ?

6. यह एक पुस्तक है।
This is a book.
What is this?

7. वह हॉकी खेल रही है।
She is playing hockey.
What is she playing?

8. वह एक कार चला रहा है।
He is driving a car.
What is he doing?

9. मैं अपने भाई से प्रेम करता हूँ।
I love my brother.
Whom do you love ?

10. मैं ने लता को एक पुस्तक दी।
I gave a book to Lata.
Who did you give a book to ?

11. मुझे भोपाल में रहना पसन्द हैं।
I like to live in Bhopal.
Where do you like to live ?

12. शाहजहॉ ने ताजमहल बनाया।
Shahjahan built the Taj.
Who built the Taj ?

Exercise

Remove ‘too’ in the following sentences :

1. He is too weak to walk.
2. She spoke too slowly for us to hear.
3. It is too cold for us to go out.
4. The boy ran too slowly to catch the bus.
5. The question is too difficult for us to solve it.
6. The room is too dark for us to work in it.
7. The tea is too hot for me to drink.
8. The fruits are too sour for us to eat them.

Transformed sentences

1. He is so weak that he cannot walk.
2. She spoke so slowly that we could not hear.
3. It is so cold that we cannot go out.
4. The boy ran so slowly that he could not catch the bus.
5. The question is so difficult that we cannot solve it.
6. The room is so dark that we cannot work in
7. The tea is so hot that I cannot drink it.
8. The fruits are so sour that we cannot eat them.

Use of Idioms and Prepositional Phrases

1. Worn out (पुराना, फटा हुआ) –
Use – My coat is really worn out.

2. Well dressed (अच्छे कपड़े पहने हुए)-
Use-He was well-dressed.

3. Poor dressed (ख़राब वस्त्र पहने हुए)-
Use-Mohan was seen poorly dressed in the party.

4. Highly priced (बहुत कीमती)-
Use-Meena bought a highly priced dress.

5. Out of danger (खतरे से बाहर)-
UseRavi had a heart attack but he is out of danger now.

6. In the middle of (बीच में,मध्य में)
Use-In the middle of the session, he fell ill.

7. In the lead (प्रारम्भ में आगे)-
Use-Mohan started his race in the lead.

8. Win someone’s heart (दिल जीत लेना)
Use-Prakash won everyone’s heart with his performance.

9. Afraid of (भयभीत)-
Use – He did his hard work but was afraid of being failed.

10. At the end of (अन्त में)-
Use-At the end of the race, he reached the point first.

11. In a bad state (ख़राब दशा में)-
Use-He continued his studies in a bad state of his health.

12. In good order (अछि दशा में)-
Use-I found my machines in the factory in good order.

13. To visit (अवलोकन करना)-
Use-Many people from other countries come to visit the Taj.

14. By the light (रात तक)-
Use-Dr. Dass was reading his book by the light of a small lamp.

15. Dressed in (कपड़े पहने)-
Use-He was dressed in white.

16. Head to foot (सिर से पैर तक)
Use-His body was covered with mud from head to foot.

17. Pull off (खींच डालना)
Use-He pull the curtain off.

18. Run away (भाग जाना)-
Use-In the end of the function, everyone runs away.

19. Go away (चले जाओ)-
Use-Go away from here.

20. Drive away (खदेड़ देना)-
Use-Robbers were driven away.

21. Got away (भाग गया)-
Use-The servant got away though his master treated him well.

22. Walk away (पीछे हटना)-
Use-we should not walk away when we find someone in need.

23. Look into (जाँच करना)-
Use-He looked into the box.

24. Look for (खोजने की कोशिश करना)-
Use-Are you still looking for a job?

25. Look upto (गणना करना)-
Use-He is looking upto him as a good soldier.

26. Look forward to (आशा करना,कामना करना)-
Use-We are looking forward to see you again.

27. Empty vessels make much noise (यथा चना बाजे घना)-
Use-Persons without perfect skill are empty vessels which make much noise.

28. Slow but steady (परिश्रमी होना)-
Use-Mohan will get success because it is true that he is slow but steady.

29. Burn the midnight oil (मेहनत करना)-
Use-These days students are burning the midnight oil.

30. Born with a silver spoon in one’s mouth (धनि परिवार में जन्म लेना)-
Use-Jawahar Lal Nehru was born with a silver spoon in his mouth.

31. Three piece (तीन भागों का)
Use-I have three piece blue suit.

32. Board a bus (बस में सवारी करना)-
Use-We have to board a bus at Pipariya to go to Panchmarhi.

33. Get lost (बिछुड़ जाना)-
Use-The child held his mother’s hand tightly so that he may not get lost.

34. Find out (खोजना)-
Use-Find out the correct solution of this sum.

35. Joy rides (प्रसन्नता देने वाली सवारियाँ)-
Use-There were many joy rides at the fair.

36. Broke down (रुक जाना)-
Use-My scooter broke down, when I was going home.

37. Keeping a watch (रखवाली करना)-
Use-Moti, the dog is keeping a watch on all the people going inside the gate.

38. Go round (चक्कर मारना)-
Use-The Principal like to go round the school to see the classes.

39. The ship of the desert (रेगिस्तान का जहाज)-
Use-The Camel is known as the ship of the desert.

40. Lame excuse (बहाना बनाना)-
UseRamesh has not done his homework so he made a lame excuse of falling sick.

41. Fool proof (पक्की सुरक्षा)-
Use-No security can be called fool proof.

42. To work hard (कठिन परिश्रम करना)-
Use-Shyam is supposed to work hard to secure good marks.

43. To turn a blind eye (आँखें मूँद लेना)-
Use-The Police turned a blind eye when they saw the thief was running away.

44. To leave one’s footprints (पदचिह्न छोड़ना)
Use-If you leave your footprints on the sand at a beach, the sea is sure to wash them away.

Homophones
(समानोच्चारीत शब्द)

उच्चारण में समान लगने वाले परन्तु अर्थ में भिन्न शब्दों को Homophone (समानोच्चारीत शब्द) शब्द कहते हैं।

I. (1) See-sea
(2) Sale-sail
(3) Sell-cell
(4) Knew-new
(5) There-their
(6) Peace-piece
(7) Check-cheque
(8) Blue-blew
(9) Heard-herd
(10) Right-write.

Use (1) See – I see a snake in the garden.
Sea – The ship is sailing on the sea

(2) Sale – National Herald has the largest sale.
Sail – The ship sails on the sea.

(3) Sell – He sells newspaper.
Cell – He lives in a small cell.

(4) Knew – He knew his address.
New – New plants are planted.

(5) There – There are four students in the class.
Their – They help their friends.

(6) Peace – There was peace in the forest.
Piece – A piece of bread was given to the dog.

(7) Check – Teacher checks the exam copy.
Cheque – Payment can also be made through cheque.

(8) Blue – He is wearing a blue shirt.
Blew – The wind blew hard.

(9) Heard – I heard a great noise.
Herd – A herd of cows was grazing.

(10) Right – Give right answer to the questions.
Write – I write a letter.

II. (1) Tire-tyre
(2) Hare-hair
(3) Quiet-quite
(4) Plain-plane
(5) Hear-here
(6) Fair fare.

Use –
(1) Tire – He is tired of hard labour.
Tyre – Tyre is a rubber covering on wheels.

(2) Hare – Hare.runs in the garden.
Hair – Hair grow on our head.

(3) Quiet – You must be quiet in the class.
Quite – We waited for quite a long period.

(4) Plain-He is a man of plain thinking.
Plane-He had to fly by a plane to Mumbai.

(5) Hear-We hear with our ears.
Here-He came here.

(6) Fair-Mohan went to a fair with his friends.
Fare-What is the fare from Bhopal to Indore ?

III.(1) Ate-He ate fruits only.
Eight-Eight boys are playing.

(2) Bye-He said goodbye to his friends.
Buy-You should buy books of good writers

(3) Weak-He is weak in English.
Week-I go to Agra twice a week.

(4) One-One thing at one time.
Won-Rana Pratap won many battles.

(5) I-i – live in Bhopal.
Eye-We see with our eyes.

IV.
(1) Bee (बी) = मधुमक्खी
Be (बी) = होना

(2) One (वन) = एक
Won (वन) = जीत

(3) Sea (सी) = समुद्र
See (सी) = देखना

(4) Eight (एट) = आठ
Ate (एट) = खाया

(5) Idle (आइड्ल्) = सुस्त,
Idol (आइड्ल) = मूर्ति।

(6) Hour (आवर्) = समय,
Our (आवर्) = हमारा।

(7) Too (टू) = भी,
Two (टू) = दो।

Antonyms (विलोम)

विरोधी अर्थ वाले शब्द Antonyms (विलोम) कहे जाते हैं।

Singular/Plural
(एकवचन/बहुवचन)

संज्ञा के दो वचन होते हैं –

1. Singular number-एकवचन (एक के लिए)
2. Plural number-बहुवचन (एक से अधिक के लिए)

(1) कुछ शब्द ऐसे होते हैं जिनका एकवचन और बहुवचन ‘एक-सा होता है। जैसे –

(2) कुछ शब्दों के अन्त में s या es लगाकर बहुवचन बनाते हैं। जैसे –


(3) कुछ शब्दों के अन्त में y हटाकर ies लगाकर बहुवचन बनाते हैं। जैसे –

(4) कुछ शब्दों के अन्त में f या fe हो तो उसे हटा कर ves लगाकर बहुवचन बनाते हैं। जैसे –

(5) कुछ अन्य शब्द जिनके बहुवचन बनाने के विशेष नियम नहीं हैं। जैसे –

Prefix and Suffix
(उपसर्ग तथा प्रत्यय)

Prefix-Primary word से पहले जोड़े गये शब्दांश Prefix कहे जाते हैं जो Primary word के अर्थ में परिवर्तन कर देते हैं –


Suffix – Primary word के बाद जोड़े गये शब्दांश Suffix कहे जाते हैं जो Primary word के अर्थ में परिवर्तन कर देते हैं –
जैसे – agree + able = agreeable.
Primary Word + Suffix


Sounds of Animals (पशुओं की आवाजौ)

1. Dogs – bark
2. Cats – mew
3. Rats – squeak
4. Lions – roar
5. Pigs – grunt
6. Horses – neigh
7. Bees – buzz
8. Goats/Sheeps – bleat
9. Cocks – crow
10. Snakes – hiss
11. Ducks – quack
12. Donkeys – bray
13. Frogs – croak
14. Birds – chirp
15. Crows – caw
16. Hens – cackle

Animals and their Homes
(पशु व अनेक घर)

Cows live in cowshed.
Lions live in den.
Dogs live in kennel.
Birds live in nest.
Pigs live in sty.
Horses live in stable.

Animals and their Young ones
(पशु और उनके बचे)

Punctuation
(पंक्चुएशन)

Punctuation का अर्थ होता है किसी वाक्य में full stop, comma आदि विराम चिन्ह का प्रयोग करना। इनके प्रयोग इस प्रकार हैं-

1. Full stop (.) हिन्दी के पूर्ण विराम (|) के स्थान पर अंग्रेजी में full stop (.) का प्रयोग होता है। इसका प्रयोग होता है।
(i) Affirmative, Negative site Imperative वाक्यों के अन्त में। जैसे –
She is playing Please, come here. She is not coming.

(ii) Abbreviations (संक्षिप्त शब्दों) तथा नामों के प्रारम्भ में। जैसे –
M.A., A. P. J. Abdul Kalam.

2. Comma (,) – Comma (अर्द्धविराम) का प्रयोग निम्न दशाओं में होता है –
(i) एक ही Part of Speech के कई शब्दों को एक-दूसरे से पृथक् करने के लिए;
जैसे – He can read, write and sing well.

(ii) And से जोड़े गये एक से अधिक शब्द समूहों को पृथक् करने के लिए;
जैसे – The minister addressed all, men and women, old and young.

(iii) Yes और No के बाद; जैसे –
Yes, I will do it.
No, I can’t do this.

(iv) Reported speech से शेष वाक्य को पृथक् करने के लिए; जैसे –
He said, “It is true.”

(v) Noun या Phrase in apposition को पृथक् करने के लिए; जैसे –
Milton, the great poet, was blind.

(vi) दिन, दिनांक या वर्ष को पृथक् करने के लिए;
जैसे – Monday, 6th June, 2007.

3. Question Mark (?) – प्रश्न चिन्ह (?)
प्रश्नवाचक वाक्यों के अन्त में लगाया जाता है; जैसे –
What is the time ?

4. Exclamation Mark (!)
इस चिन्ह का प्रयोग –
(i) Interjection के बाद में होता है; जैसे – Oh ! Alas!

(ii) इस चिन्ह का प्रयोग उन वाक्यों के अन्त में भी होता है जो गहन संवेग को व्यक्त करते हैं; जैसे –
What a beautiful picture !

5. Inverted Commas (“….”) – Direct Speech में किसी के कहे गये यथार्थ शब्दों को शेष वाक्य से पृथक् करने के लिए Inverted Commas आदि और अन्त में लगाये जाते हैं; जैसे –
He said, “I shall win.”

6. Apostrophe (‘) – इसका प्रयोग होता है।
(i) अक्षरों के लोप को प्रकट करने के लिए
Don’t, Won’t, Can’t

(ii) Possessive case बनाने के लिए Sita’s pen.

(iii) अक्षरों तथा संख्याओं का बहुवचन बनाने के लिए –
Add three 4’s and two 3’s.

Capital Letters – Capital letters का प्रयोग होता –

(i) वाक्य के प्रथम शब्द का प्रथम अक्षर लिखने के लिए।
He is my son.

(ii) Proper Nouns और उससे बने हुए Adjectives के प्रथम अक्षर को लिखने के लिए –
Asha, Delhi, Indian.

(iii) Pronoun I को लिखने के लिए …..
I am a teacher.

(iv) God, Almighty, Lord शब्दों के लिए प्रयुक्त Pronouns के प्रथम अक्षर लिखने के लिए।

Exercise

Punctuate the following sentences

1. he sits next to his friend sonu his father teaches geography.
2. come here sonam i have a rupee for you said rajan.
3. is this your final decision asked ramesh.
4. during our journey to delhi we slept read and played cards.
5. don’t worry said akash i will give the pen to him.

Answer:

1. He sits next to his friend, Sonu. His father teaches Geography.
2. “Come here, Sonam. I have a rupee for you,” said Rajan.
3. “Is this your final decision ?” asked Ramesh.
4. During our journey to Delhi, we slept, read and played cards.
5. “Don’t worry”, said Akash, “I will give the pen to him.”

MP Board Class 7th English Solutions

MP Board Class 7th General English Solutions Revision Exercises 3

Read and Learn (पढ़ो और याद करो) :
Students should do themselves.

Comprehension (बोध प्रश्न):

(A) Answer These questions :
(इन प्रश्नों के उत्तर दीजिए)

Question 1.
What is the poem Lohri about ?
Answer:
The poem is about the festival of ‘Lohri’.

Question 2.
Where did the five friends go one day?
Answer:
The five friends went to the fair one day.

Question 3.
Why is the story called, “One Way Ticket” ?
Answer:
All the five friends collected their money they had and then only they were able to buy a one way ticket for the return journey.

Question 4.
Who built the buildings at Orchha ?
Answer:
Bundela kings built the buildings at Orchha.

Question 5.
What were Laxmi Bai’s last words?
Answer:
The last words of Maharani Laxmi Bai were, “Let no Britisher touch my body.”

(B) Read the following and tick true or false :
(निम्नलिखित वाक्यों को पढ़कर सत्य/असत्य पर चिन्ह लगाइए)

(i) Manu was a cowardly girl. T/F
(ii) The five friends had no money to return home. T/F
Answer:
(i) False
(ii) False

(C) Tick the correct option:
(सही विकल्प पर चिह्न लगाइए)

(i) Bonfires consume a lot of/a little wood.
Answer:
a lot of

(ii) The Bundela Kings made Orchha/Sanchi their capital.
Answer:
Orchha.

(D) Fill in the blank spaces :
(रिक्त स्थान भरिए)

(i) Lohri celebrates the harvesting of new …………..
(ii) Laxmi Bai took training in martial …………..
Answer:
(i) crop
(ii) arts.

Word Power (शब्द समर्थ):

(A) Write the homophones for :
(समान स्वर वाले शब्दों को लिखो।)
(i) hear
(ii) write
Answer:
(i) here
(ii) right.

(B) Write one work for each phrase given below:
(नीचे दिए प्रत्येक शब्द समूह के लिए एक शब्द लिखिए।)

(i) A monument built in memory of someone who died somewhere else.
(ii) Words written in memory of a person who has died; an inscription on a tombstone.
Answer:
(i) Cenotaph
(ii) epitaph.

(C) Write the meanings of the following words:
(निम्न शब्दों के अर्थ लीखिए)

(i) merge
(ii) rear
Answer:
(i) mix
(ii) to bring up.

(D) Classify the following into cenotaph and tomb:
(निम्न को स्मारक और मकबरे में वर्गीकृत कीजिए।)
(i) The Taj Mahal.
(ii) Amar Jyoti at Vijay Chowk.
(iii) Rajghat.
(iv) Humayun Ka Makbara
(v) Chhatries at Orchha
(vi) Samadhi of Laxmi Bai
Answer:
Cenotaph-Amar Jyoti at Vijay Chowk, Rajghat, Chhatries at Orchha, Chhatries at Maheswar and Indore.
Tomb – The Taj Mahal, Humayun Ka Makbara, Samadhi of Laxmibai.

Grammar in Use (व्याकरण प्रयोग):

(A) Fill in the blank spaces using ‘between’ and ‘among’:
(between और among का प्रयोग कर रिक्त स्थान भरिए)

(i) The letter S comes ……… the letter R and T of the English alphabet.
(ii) She works ………. the poor.
Answer:
(i) between
(ii) among.

(B) Combine the sentences using ‘where’ and ‘when’:
(Where और When का प्रयोग कर वाक्यों को जोड़िए।)

(i) I found the pen. I had kept it.
Answer:
I found the pen where I had kept it.

(ii) Sona called me. I was reading.
Answer:
Sona called me when I was reading.

(C) Encircle the correct adjective for the following nouns :
(निम्नलिखित संज्ञाओं के लिए सही विशेषण पर गोला लगाओ)

(D) Make more words by adding ‘ly’.
(‘ly’ लगाकर अधिक शब्द बनाइए)

(i) brave – bravely
(ii) fearless – fearlessly
(iii) extreme – extremely

(E) Punctuate the following paragraph.
(निम्न अनुच्छेद में विराम चिन्ह का प्रयोग कीजिए।)
Answer:
Once Bishni, Kishto, Gittoo and Lambu went to see a Bal mela in a school. There, they saw many Science models made by students. Bishni asked, “What is the model about ?” Kishto explained, “This is about a water pump.”

Let’s Write (आओ लिखें) :

Question 1.
Write about the Holi celebration in one paragraph.
(होली पर्व के बारे में एक अनुच्छेद लिखिए।)
Answer:
Holi is the festival of colours. The people express their happiness by throwing colours on their friends, relatives and neighbours. They make fun. They use dry and wet colours. Relating to the festival and season people are lost in singing songs. They feel happy by welcoming their friends with sweetmeats and tea or coffee or cold drink. Sugarcane fields look full of cheerfulness of the farmers who work there. Grain fields look very beautiful. Some people throw mud on one another and shout. Everyone small or big bears a smile on his face.

(ii) Write a paragraph about Orchha.
(ओरछा के बारे में एक अनुच्छेद लिखिए।)

(iii) Write five lines about the qualities of Maharani Laxmi Bai.
(महारानी लक्ष्मी बाई के गुणों के बारे में पाँच लाइनें लिखिए)
Answer:

Maharani Laxmi Bai was the queen of Jhansi. She was brave, courageous and bold from her early childhood. She was skilled in horse riding, shooting, wrestling and all the martial arts and continued to practise them even after her marriage with Gangadhar Rao, the king of Jhansi.

When Britishers declared to merge Jhansi with British empire, after her husband’s death, she opposed it and bravely fought against them not thinking that she was a woman. She was a great patriot. She tied her son to her back and led her army against the British. She fought courageously till her last breath and did not let any Britisher touch her living or dead.

Let’s Do It (आओ इसे करें):

(A) Read the given paragraph and write answers to the questions that follow :
(दिए गए अनुच्छेद को पढ़कर उसके नीचे दिए प्रश्नों के उत्तर लिखिए।)

Question 1.
Why do birds build nests?
Answer:
Birds build nests to lay their eggs which need to be kept warm.

Question 2.
Which bird makes its nest out of mud ?
Answer:
Swallows and martins make their nests out of mud.

Question 3.
What does a tailor bird do to build its nest ?
Answer:
A tailor bird sews leaves together to make its nest.

Question 4.
Which birds make their nests on the ground ? Why?
Answer:
Ostrich and Kingfisher make their nest on the ground because they cannot fly.

Question 5.
Which birds lay their eggs in other birds, nests?
Answer:
Cockoo lays its eggs in other bird’s nests.

(B) Match these words with words opposite in their meaning :
(इन शब्दों को उनके विपरीतार्थक शब्दों से मिलान कीजिए)

1. many – (a) similar
2. safe – (b) unsafe
3. strong – (c) uncomfortable
4. different – (d) few
5. comfortable – (e) weak
Answer:
1. → (d)
2. → (b)
3. → (e)
4. → (a)
5. → (c).

MP Board Class 7th English Solutions

MP Board Class 7th Science Solutions Chapter 13 Motion and Time

Motion and Time Intex Questions

Question 1.
Paheli wondered how time was measured when pendulum clocks were not available?
Answer:
Many times measuring devices were used in different parts of the world before the pendulum clocks became popular. Water clocks, sand clocks and sundials are some examples of such devices.

Question 2.
Boojho wants to know whether there is any device that measures the speed?
Answer:
Yes, speedometer.

Activities

Activity – 1
Table gives some common examples of motions. Identify the type of motion in each case?
Answer:
Some examples of different types of motion

Activity – 2
Draw a straight line on the ground with chalk powder or lime and ask one of your friends to stand 1 to 2 m away from it. Let your friend gently roll a ball along the ground in a direction perpendicular to the line. Note the time at the moment the ball crosses the line and also when it comes to rest (Fig.) How much time does the ball take to come to rest? Measure the distance between the point at which the ball crosses the line and the point where it comes to rest. You can use a scale or a measuring tape. Let different groups repeat the activity. Record the measurements in Table. In each case calculate the speed of the ball?

Answer:

Activity – 3
The unit of speed in the given table is in km/h. Change this speed in to m/s?
Answer:
Speed of some animals.

Motion and Time Text Book Exercises

Question 1.
Classify the following as motion along a straight line, circular or oscillatory motion:

1. Motion of your hands while running.
2. Motion of a horse pulling a cart on a straight road.
3. Motion of a child in a merry – go – round.
4. Motion of a child on a see – saw.
5. Motion of the hammer of an electric bell.
6. Motion of a train on a straight bridge.

Answer:

1. Oscillatory
2. Straight line
3. Circular
4. Oscillatory
5. Oscillatory
6. Straight line.

Question 2.
Which of the following are not correct?

1. The basic unit of time is second.
2. Every object moves with a constant speed.
3. Distances between two cities are measured in kilometres.
4. The time period of a given pendulum is not constant.
5. The speed of a train is expressed in m/h.

Answer:

2. Every object moves with a constant speed.
5. The speed of a train is expressed in m/h.

Question 3.
A simple pendulum takes 32 s to complete 20 oscillations?What is the time period of the pendulum?
Answer:
Given, time taken to complete 20 oscillations = 32 seconds
∴Time taken to complete 1 oscillation = \(\frac{32}{20}\)s = 1.6 s
Thus, the time period of pendulum is 1.6 s

Question 4.
The distance between two stations is 240 km. A train takes 4 hours to cover this distance. Calculate the speed of the train?
Answer:
Given, distance between two stations = 240 km and time taken to cover this distance = 4 hour
We know that,

\(\frac{240}{4}\) = 60 km/hour.
Thus, the speed of the train is 60 km/hour.

Question 5.
The odometer of a car reads 57321.0 km when the clock shows the time 08.30 AM. What is the distance moved by the car, if at 08:50 AM, the odometer reading has changed to 57336.0 km? Calculate the speed of the car in km/min during this time. Express the speed in km/h also?
Answer:
Given, reading of odometer at time 08:30 AM = 57321.0 km and reading of odometer at time 08:50 AM = 57336.0 km.
∴Distance covered by car = (57336.0 – 57321.0) km = 15 km and Time taken = 8.50 – 8.30 = 20 minutes
We know that,

Question 6.
The odometer of a car reads 57321.0 km when the clock shows the time 08.30 AM. What is the distance moved by the car, if at 08:50 AM, the odometer reading has changed to 57336.0 km? Calculate the speed of the car in km/min during this time. Express the speed in km/h also?
Answer:
Given, reading of odometer at time 08:30 AM = 57321.0 km and reading of odometer at time 08:50 AM = 57336.0 km
∴Distance covered by car = (57336.0 – 57321.0) km = 15 km and Time taken = 8.50 – 8.30 = 20 minutes We know that,

Thus, the distance between Salma’s school from her house is 1800 m or 1.8 km.

Question 7.
Show the shape of the distance – time graph for the motion in the following cases:

1. A car moving with a constant speed.
2. A car parked on a side road.

Answer:

Question 8.
Which of the following relations is correct?

Answer:

Question 9.
The basic unit of speed is:
(a) 100km.
(b) m/min
(c) km/h
(d) m/s.
Answer:
(d) m/s.

Question 10.
A car moves with a speed of 40 km/h for 15 minutes and then with a speed of 60 km/h for the next 15 minutes. The total distance covered by the car is:
(a) 100 km
(b) 25 km
(c) 15 km
(d) 10 km.
Answer:
(b) 25 km.
Distance travelled in first 15 minutes = Speed x Time = 40 km/h x 15 minutes.
= 40 km/h × \(\frac{15}{60}\) hour
= 10 km
Distance travelled in last 15 minutes = Speed x Time = 60 km/h x 15 minutes
= 60 km/h × 15 minutes
= 60 km/h × \(\frac{15}{60}\) hour
= 15 km.
Total distance = (10 + 15) km = 25 km.

Question 11.
Suppose the two photographs, shown in Fig. (a) and Fig. (b) had been taken at an interval of 10 seconds. If a distance of 100 meters is shown by 1 cm in these photographs, calculate the speed of the blue car?


Answer:
Speed = \(\frac{100 km}{10 h}\) = 10 km/h.

Question 12.
Fig. shows the distance – time graph for the motion of two vehicles A and B. Which one of them is moving faster?

Answer:
Car A is moving faster.

Question 13.
Which of the following distance – time graphs shows a truck moving with speed which is not constant?

Answer:
(iii)

Motion and Time Additional Important Questions

Objective Type Questions

Question 1.
Choose the correct alternative :

Question (a)
The time taken for one oscillation is called its
(a) Pitch
(b) Frequency
(c) Vibration
(d) Time period.
Answer:
(d) Time period.

Question (b)
1 minute has?
(a) 30 second
(b) 60 second
(c) 100 second
(d) None of these.
Answer:
(b) 60 second

Question (c)
The smallest time interval that can be measured with commonly available clocks and watches is?
(a) 1 second
(b) 1 minute
(c) 1 hour
(d) None of these.
Answer:
(c) 1 hour

Question (d)
The ages of stars and planet are often expressed in –
(a) billions of years
(b) days
(c) years
(d) None of these.
Answer:
(a) billions of years

Question (e)
The distance moved by a vehicle can be measured by –
(a) speedometer
(b) odometer
(c) regulator
(d) None of these.
Answer:
(b) odometer

Question (f)
The distance – time graph of a body moving with uniform speed is –
(a) a curve
(b) a straight line
(c) line parallel to x – axis
(d) None of these.
Answer:
(b) a straight line

Question 2.
Fill in the blanks:

1. We shall use the term speed for average ……………………….
2. An object moving along a straight line with a constant speed is said to be in …………………………
3. The to and fro motion of a simple pendulum is an example of a ……………….. or ……………………. motion.
4. The basic unit of time is a ……………………….
5. The basic unit of speed is ………………………..
6. Periodic events are used for the measurement of ……………………….
7. The distance – time graph for the motion of an object moving with a constant speed is a ……………………
8. The speedometer records the speed in ……………………..
9. Odometer is used to measure ………………………
10. The distance moved by an object is a unit time is called its ………………………….

Answer:

1. Speed
2. Uniform speed
3. Periodic, oscillatory
4. Second
5. m/s
6. Time
7. Straight line
8. km/h
9. Distance
10. Speed.

Question 3.
Which of the following statements are true (T) or false(F).

1. The distance moved by objects in a given interval of time can help us to decide which one is faster or slower.
2. We shall not use the term speed for average speed.
3. The to and fro motion of a simple pendulum is an example of a periodic motion.
4. Janter Manter in Delhi and Jaipur have big Sundials.
5. In non – uniform motion, the speed of an object changes.
6. Clocks or watches are perhaps the most common time measuring devices.
7. Different units of time are used depending on the need.

Answer:

1. True
2. False
3. True
4. True
5. True
6. True
7. True.

Motion and Time Very Short Answer Type Questions

Question 1.
Define motion.
Answer:
Motion is the change in position of a body with respect to line and its surroundings.

Question 2.
What type of motion do the vehicles on a straight road perform?
Answer:
The vehicles perform rectilinear motion on the road.

Question 3.
What type of motion does the wheel of a bicycle perform?
Answer:
The wheel of a bicycle perform rotatory or circular motion.

Question 4.
What is uniform motion?
Answer:
Motion of a body along a straight line covering equal distances in equal intervals of time is called uniform motion.

Question 5.
Give two example of non – uniform motion?
Answer:

1. Motion of the train when its driver applies breaks.
2. Motion of the cricket ball when the bowler throws the ball and the ball is hit by the player.

Question 6.
Give two example of periodic motion?
Answer:

1. Rotation of earth on its axis.
2. Moon moves around the earth.

Question 7.
What is oscillatory motion?
Answer:
The to and fro motion is called periodic or an oscillatory motion.

Question 8.
An object is hung from a spring is pulled down and left? What type of motion does the object perform?
Answer:
The object perform oscillatory motion which is also a periodic motion.

Question 9.
Write the formula for speed?
Answer:

Question 10.
What is the unit of speed?
Answer:
Unit of speed is meter per second.

Question 11.
A snail covers a distance of 1 meter in 10 sec. What is the speed of the snail?
Answer:
image
= 0.1 ms^-1
= 0.1 m per sec.

Question 12.
What happens to the speed of your bicycle when you pedal faster?
Answer:
On pedalling fast the speed of bicycle increase.

Question 13.
“Speed of a car is 8 km/h”. What does it mean?
Answer:
When we say that a car is moving with a speed of 80 kilometer per hour, it implies that it will cover a distance of 80 kilometre in one hour.

Question 14.
Define a day?
Answer:
The time between one sunrise and the next is called a day.

Question 15.
What is month ?
Answer:
A month is measured from one new moon to the next.

Question 16.
What is year?
Answer:
A year is fixed as the time taken by the earth to complete one revolution of the sun.

Question 17.
What is bob?
Answer:
The metallic ball is called bob of the pendulum.

Question 18.
What is the use of stop – watch?
Answer:
Stop – watch is used to measure exact time in case of atheletic events as it can be stopped and started any moment.

Question 19.
When you travel in bus or car then, generally, what kind of motion it is?
Answer:
Linear motion.

Question 20.
There is 100 metres line on which two sprinters have to run, when they run, what kind of motion it will be?
Answer:
Linear motion.

Question 21.
See the picture and tell whose speed is more:


Answer:
Speed of tiger is more than the speed of horse.

Motion and Time Short Answer Type Questions

Question 1.
Define periodic motion?
Answer:
Periodic motion:
The motion of a body which is repeated at regular intervals of time is called periodic motion. In periodic motion, a body covers equal distances in equal intervals of time; e.g. revolution of earth round the sun, the motion of moon round the earth, the motion of a swing, the motion of a pendulum, etc.

Question 2.
Define non – periodic motion?
Answer:
Non – periodic motion:
The motion of a body which is not repeated at regular intervals of time is called non – periodic motion. In non – periodic motion, a body does not cover equal distances in equal intervals of time; e.g. an athelete running on a track, a moving car on busy road, etc.

Question 3.
Define oscillatory motion?
Answer:
Oscillatory motion:
A body is said to be in oscillatory motion when it moves to and fro about a fixed point; e.g. the pendulum of a wall clock (Fig.), a swing, a wire of sitar when plucked, striking of drum, etc. Mostly the hanging objects show oscillatory motion.

Question 4.
How can we make a pendulum of air one? What is the time – period of a pendulum?
Answer:
We can make a pendulum by suspending a metal ball with a cotton thread. The other end of the thread can be tied to same support. The time taken by a pendulum to complete its to and from movement i.e., one oscillation is called the time period of the pendulum.

Question 5.
One student reaches school in 1 hour by travelling a distance of 8 km from his house by a cycle and the other student reaches school in one and half hours by travelling a distance of 12 kms from his house by cycle. Tell whose speed was slow?
Answer:

From above calculations it is clear that the speed of both the students is same.

Question 6.
What are quartz clocks? Give a diagram of digital clock?
Answer:
Now a days most clocks or watches have an electric circuit with one or more cells. These clocks are called quartz clocks. The time measured by quartz clocks is much more accurate than that by the clocks available earlier.

Question 7.
Mark x – axis, y – axis, origin on a graph paper?
Answer:

Motion and Time Long Answer Type Questions

Question 1.
Write briefly about the development of pendulum clock?
Answer:
There is an interesting story about the discovery that the time period of a given pendulum is constant. You might have heard the name of famous scientist Galileo Galilie (A.D. 1564 – 1642). It is said that once Galileo was sitting in a church. He noticed that a lamp suspended from the ceiling with a chain was moving slowly from one side to the other.

He was surprised to find that his pulse beat the same number of times during the interval in which the lamp completed one oscillation. Galileo experimented with various pendulums to verify his observation. He found that a pendulum of a given length takes always the same time to complete one oscillation. This observation led to the development of pendulum clocks. Winding clocks and wristwatches were refinements of the pendulum clocks.

Question 2.
Discuss in details about the different range to measure time interval?
Or
Discuss the different units for measuring time interval?
Answer:
The smallest time interval that can be measured with commonly available clocks and watches is one second. However, now special clocks are available that can measure time intervals smaller than a second. Some of these clocks can measure time intervals as small as one millionth or even one billionth of a second. We might have heard the terms like microsecond and nanosecond. One microsecond is one millionth of a second. A nanosecond is one billionth of a second.

Clocks that measure such small time intervals are used for scientific research. The time measuring devices used in sports can measure time intervals that are one tenth or one hundredth of a second. On the other hand, times of historical everts are stated in terms of centuries or millenniums. The ages of stars and planet are often expressed in billions of years.

Question 3.
Draw a bar graph to show the runs scored by a team in each over?

Answer:

Question 4.
Draw a pie chart to show the composition of air?
Answer:

Question 5.
Write down the steps to make a distance – time graph?
Answer:
We can make the graph by following steps:
Step 1.
Draw two perpendicular lines to represent the two axes and mark them as OX and OY as shown in figure.

Steps 2.
Decide the quantity to be shown along the x – axis and that to be shown along the y – axis. In this case we show the time along the x – axis and the distance along the y – axis.

Steps 3.
Choose a scale to represent the distance and another to represent the time on the graph. For the motion of the car scales could be
Time : 1 min = 1 cm
Distance : 1 km = 1 cm

Step 4.
Mark values for the time and the distance on the respective axes according to the scale chosen. For the motion of the cat let mark the time 1 min, 2 min,..,on the origin x – axis from the origin Similarly, mark the distance 1 km. 2 km… on the y – axis.

Steps 5.
Now you have to mark the points on the graph paper to represent each set of values for distance and time.

Step 6.
Join all the points on the graph as shown in figure. It is a straight line. This is the distance-time graph for the motion of the car.
Note:
If the distance – time graph is a straight line, it indicates that the object is moving with a constant speed. However, if the speed of the object keeps changing, the graph can be of any shape.

MP Board Class 7th Science Solutions