MP Board Class 6th Science Solutions Chapter 14 Water
Water Textbook Exercises
Fill in the blanks in the following:
- The process of changing of water into its vapour is called ……………….
- The process of changing water vapour into water is called ………………
- No rainfall for a year or more may lead to ……………… in that region.
- Excessive rains may cause ………………..
State for each of the following whether it is due to evaporation or condensation:
- Water drops appear on the outer surface of a glass containing cold water.
- Steam rising from wet clothes while they are ironed.
- Fog appearing on a cold winter morning.
- Blackboard dries up after wiping it.
- Steam rising from a.hot girdle when water is sprinkled on it.
Which of the following statements are “true”?
- Water vapoure is present in air only during the monsoon.
- Water evaporates into air from oceans, rivers and lakes but not from the soil.
- The process of water changing into its vapour, is called evaporation.
- The evaporation of water takes place only in sunlight.
- Water vapour condenses to form tiny droplets of water in the upper layers of air where it is cooler.
Suppose you want to dry your school uniform quickly. Would spreading it near and anghiti or heater help? If yes, how?
Yes, if we want to dry our school uniform quickly, we should spread our clothes near a anghiti or heater. The reason is that near anghiti or heater, temperature is more so water evaporation from the clothes will be faster, hence the clothes dry quickly.
Take out a cooled bottle of water from refrigerator and keep it on a table. After some time you notice a puddle of water around it Why?
When we keep a cooled bottle of water taking out from a refrigerator we notice some puddles of water around it. This is due to the water – vapour near the surrounding atmosphere, condenses and deposites around the cooled water bottle. Water vapour always remains in the atmosphere.
To clean their spectacles, people often breathe out on glasses to make them wet. Explain why the glasses become wet.
When we breathe on the spectacles, water vapour comes out from our breathe, and they condenses into water droplets when they come in contact of glass, because the glasses are cooler that the water vapours. Hence, the glasses becomes wet due to water puddles.
How does clouds formed?
There is a continuous evaporation of water from surfaces of sea, rivers, lakes, etc. As we go higher from the surface of the earth, it gets cooler. When the air moves up, it gets cooler and cooler.
At sufficient height, the air becomes so cool that the water vapour present in it condenses to form tiny drops of water called droplets. It is these tiny droplets that remain floating in air and appear to us clouds.
When does a drought occur?
If it does not rain in a region for a year or more. The soil continues to lose water by evaporation and transpiration. Since it is not being brought back by rain, the soil becomes dry. The level of water in wells and in ponds of the region goes down and some of them may also became scarce. This may lead to drought.
Projects and Activities
List all the activities for which you use water in a day?
Write a slogan of your own on the topic ‘save water”?
“Save Every Drop of Water”.
Water Text Book Questions
Boojho wonders whether people living in different regions of our country get the same amount of water. Are there regions where people not get adequate amount of water? How do they manage?
The people living in different areas or regions of our country do not get the same amount of water. There are so many places in Rajasthan, where people do not get adequate amount of water. They manage their needs by storing the water.
Paheli wants to tell you that about two glasses of water are required to produce each page of a book.
Boojho wants you to imagine a day in your life when water supply through taps is not available. So, you have to fetch it yourself from a far away place. Would you use the same amount of water as on any other day?
No, on such a day we will use less amount of water.
Paheli has noticed dew on leaves of grass on winter mornings. Did you notice something similar on leaves or metal surfaces like iron grills and gates on a cold morning? Is this also due to condensation? Do you see this happening on hot summer mornings?
Yes, it is due to condensation. This does not happening on hot summer mornings.
Boojho has noticed fog near the ground in winter mornings. He wonders if this is also condensation of water vapour near the ground. What do you think?
Yes, it is condensation of water vapour near the ground.
Water Additional Important Questions
Water Objective Type Questions
Choose the correct answer:
Water is –
(a) A mixture
(b) A compound
(c) An element
(d) None of these.
(b) A compound
The purest form of natural water is –
Salinity of sea water is about –
(d) none of these.
The major source of water on the earth is –
(a) Ground water
(b) Rain water
(c) Sea water
(d) Surface water.
(b) Rain water
Drinking water is known as –
(a) Soft water
(c) Fresh water
(d) Potable water.
(d) Potable water.
Fill in the blanks –
- Water is one of the basic constituents of all ………………… things.
- Water is required in the home for …………………. and ……………………
- ………………… is essential for germination of seeds.
- Water is essential for all animals and ………………….
- Electricity can be generated by ………………….
- In cold countries ………………….. water is used to worm their houses.
- A car radiator is filled with water to keep the engine …………………
- Pure water has ……………….. taste.
- When water is boiled it changes to …………………
- The boiling point of water is ………………………
- Drinking, washing, bathing
Which of the following statements are true: (T) or false (F):
- Water from all sources is fit for drinking.
- Chemicals are added in water to kill the germs present in it.
- Sea water is a saline water.
- Rain water is present form of water.
- Water obtained from different.sources have same taste.
- Pure water is blue in colour.
- Water dissolved many substances, therefore it is a good solvent.
- Water cycle deals with the circulation of water on the earth.
- Whole of rain water goes to sea.
- Water cycle makes the balance of water on the earth.
- In atmosphere, temperature decreases with height.
- Rain forms due to evaporation of clouds.
Match the items in Column A with Column B:
Water Very Short Answer Type Questions
What part of earth is covered with water?
Three – fourth of earth is covered with water.
How much water is present in a –
They have following percentage of water:
- Tree – 60%
- Man – 70%
- Elephant – 80%.
How does a plant get water for living?
A plant gets water from soil through its roots.
How does a plant lose it extra water absorbed by roots?
Leaves of a plant has tiny pores in it. It loses extra water through these tiny pores.
What is transpiration?
Plants lose their extra water continuously from the tiny openings present in their leaves. This process is known as transpiration.
Mention three sources of water.
Which is the largest sources of water on earth?
The largest source of water is ocean.
What chemicals would you use to kill the germs present in water?
Chlorine is added to water to kill the germs present in water.
What are the different methods to make water fit for use?
Water can be made fit for use by the following methods:
- Treating water with chemicals like chlorine.
What is the saline water?
Water which contains large amount of dissolved salts is called saline water.
Is water obtained from pond or lake fit for drinking?
No, water obtained from pond or lake is not always fit for drinking. It may contain some impurities.
Why can’t we use sea water for drinking?
Sea water is salty and hence cannot be used at home and in agriculture.
State three physical properties of water?
Water is colourlesss, odourless, tasteless and transparent liquid.
What do you mean by water cycle in nature?
The change of water from one form to another over and over in makes the water cycle in nature.
Is water obtained from every source fit for drinking?
No, it is not safe for drinking. Before drinking it should be purified.
Why should water be conserved?
Water is a natural resource. Once it is polluted it is difficult and expensive to purify it. Therefore, it should not be wasted but conserved.
How does forest help us?
Forests increase in rainfall which increases the water level in wells, lakes and rivers.
Which is the purest form water?
Rain water is the purest form of water.
What problems are faced by the people in drought areas?
In drought areas, people face many problems. It is difficult to get food and fodder. Animals and plants will die in the absence of water.
Why should we protect our forest and grow more trees?
We should protect our forest and also grow more trees because they help in rainfall. They increase rainfall. So we should grow more trees.
Name two pollutants.
Water pollutants are household waste and industrial waste like detergents, chemicals like nitrates, phosphates etc.
Water Short Answer Type Questions
Define ground water.
The ground water is actually rain water which mainly comes from seepage of water accumulated under the ground. Rain water percolates into the soil and reaches under the ground where water quantity increases and air decreases. This reserve water under the ground is called ground water. Open wells are fed by ground water. Ground water is the source of many lakes as well The more land pumps or tubewells that are used in an area, the deeper we need to dig to find this ground water.
What makes the sea water so saline?
Rivers flowing from different places bring water containing dissolved salts and minerals into the sea. Sea water is continuously evaporated by the heat of 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 in increasing.
Why is the water cycle important?
Water cycle is important to us because of the following:
- It restores the supply of water in nature.
- It regulates the temperature of atmosphere.
- It regulates the weather or reasons.
Mention five uses of water?
Water is useful in many ways like:
- For drinking, washing, cooking and other household works.
- It is used for generation of energy in dams.
- It is used for irrigation of fields for proper crop yield.
- It is used in industries.
- It is used in car to cool radiators.
Why is conservation of water essential?
Water is essential for life. There are many sources of water, but water obtained from these sources are not fit for drking. To make it safe for drinking, it has to undergo many methods of purification, which is a long process. So water must be conserved. It means, it should be carefully and economically used.
Water Long Answer Type Questions
How will you show that water is essential for the germination of seeds?
The following experiment shows that the water is essential for the germination of seeds:
Take two petrydishes. Put some gram seeds (say 20) in both the dishes. Add some water in dish 1 and keep dish 2 dry. Keep them for 6 hours. Now remove the water and keep wet cotton wool in dish 1, and dish 2 should be remained as such. Keep them for two days. After two days we will see that only moist seeds have been germinated while dry seeds remain as such. This shows that water is essential for germination.
Briefly describe water cycle in nature.
The change of water from one form to another over and over again makes the water cycle in nature. Water cycle involves evaporation, condensation and precipitation. The water from the surface of sea, river, lakes or ponds is evaporated in the form of water vapours. Water is also evaporated from the surface of plants as transpiration.
These vapours rise high up in air and condense in the form of clouds. When temperature is low, the water precipitates in the form of rain, hails or snow to restore the supply of water back to the earth to repeat the cycle.
How can water wastage be minimised?
The water which is safe for drinking is not available in plenty. Thus everyone should make efforts to save water. We should also minimise the water pollution.
We can minimise water wastage by following methods:
- Pollution of water at sources should be minimised.
- By using water carefully.
- By growing forest. It helps in more rainfall and hence the excess of water will be available.
- More number of dams on rivers will also help in wastage of rain water.
- Rain water may also be collected.
What if it rains heavily? Discuss a scene of a flood area?
The time, duration and the amount of rainfall varies from place to place. In some parts of the world it rains throughout the year while there are places where it rains only for a few days.
In our country, most of the rainfall occurs during the monsoon season. Rains bring relief especially after hot summer days. The sowing of many crops depends on the arrival of monsoon.
However, excess of rainfall may lead to many problems [see figure (a)]. Heavy rains may lead to rise in the level of water in rivers, lakes and ponds. The water may then spread over large areas causing floods. The crops fields, forests, villages, and cities may get submerged by water [Fig. (b)]. In our country, floods cause extensive damage to crops, domestic animals, property and human life.
During floods, the animals living in the water also get carried away with the waters. They often get trapped on land areas and die when floodwater recedes. Rains also affect the animals living in the soil.
What is rain water harvesting? How is it done? Discuss any two techniques of rainwater harvesting.
One way of increasing the availability of water is to collect rainwater and store it for later use. Collecting rainwater in this way is called rainwater harvesting. The basic idea behind rainwater harvesting is “Catch water where it falls”. It flows into the drains, isn’t it? From roads and buildings water goes to rivers or lakes, which could be far away. A lot of effort will then be required to get this water back into our homes as the water did not seep into the ground.
The two techniques of rainwater harvesting are:
1. Rooftop rainwater harvesting:
In this system the rainwater is collected from the rooftop to a storage tank, through pipes. This water may contain soil from the roof and need filtering before it is used. Instead of collecting rainwater in the tank, the pipes can go directly into a pit in the ground. This then seeps into the soil to recharge or refill the ground water.
2. Another option is to allow water to go into the ground directly from the roadside drains that collect rainwater.