In this article, we will share MP Board Class 8th Science Solutions Chapter 4 Materials: Metals and Non-Metals Pdf, These solutions are solved subject experts from the latest edition books.
MP Board Class 8th Science Solutions Chapter 4 Materials: Metals and Non-Metals
MP Board Class 8th Science Materials: Metals and Non-Metals NCERT Textbook Exercises
Which of the following can be beaten into thin sheets?
Which of the following statements is correct?
(a) All metals are ductile.
(b) All non-metals are ductile.
(c) Generally, metals are ductile.
(d) Some non-metals are ductile.
(c) Generally metals are ductile.
Fill in the blanks:
(a) Phosphorus is a very …………… non – metal.
(b) Metals are …………….. conductors of heat and
(c) Iron is ……….. reactive than copper.
(d) Metals react with acids to produce ………….. gas.
(b) good, electricity,
Mark ‘T’ if the statement is true and ‘F’ if it is false.
(a) Generally, non-metals react with acids. [ ]
(b) Sodium is a very reactive metal. [ ]
(c) Copper displaces zinc from zinc sulphate solution. [ ]
(d) Coal can be drawn into wires. [ ]
Some properties are listed in the following table. Distinguish between metals and non-metals on the basis of these properties.
Give reasons for the following:
(a) Aluminium foils are used to wrap food items.
(b) Immersion rods for heating liquids are made up of metallic substances.
(c) Copper cannot displace zinc from its salt solution.
(d) Sodium and potassium are stored in kerosene.
(a) Aluminium foils are used to wrap food items because aluminium is a light metal which can be converted into very thin sheets.
(b) Immersion rods are made up of metallic substances because metals are good conductors of heat and electricity.
(c) Copper cannot displace zinc from its salt solution because copper is less reactive than zinc.
(d) Sodium and potassium react vigorously with oxygen and water. Therefore, they are stored in kerosene.
Can you store lemon pickle in an aluminium utensil? Explain.
Lemon pickle contains acids which tends to attack aluminium and iron forming poisonous salts. Therefore, aluminium and iron containers are not used to store pickles.
Match the substances given in column A with their uses given in column B.
(i) (d), (ii) (e), (iii) (c), (iv) (f), (v) (b), (vi) (a).
What happens when
(a) Dilute sulphuric acid is poured on a copper plate?
(b) Iron nails are placed in copper sulphate solution?
Write word equations of the reactions involved.
(a) When dilute sulphuric acid is poured on a copper plate, it reacts to form copper sulphate and hydrogen.
Copper + Sulphuric acid → Copper sulphate + Hydrogen
(b) When iron nails are placed in copper sulphate solution, iron being more reactive than copper, displaces copper to form ferrous sulphate solution.
The blue colour is, thus, changed to light green.
Iron + Copper sulphate → Nail Solution (Blue)
Ferrous sulphate + Copper Solution (Reddish brown)
Saloni took a piece of burning charcoal and collected the gas evolved in a test tube.
(a) How will she find the nature of the gas?
(b) Write down avoid equations of all the reactions taking place in this process.
(a) She will bring a moist blue litmus paper near the mouth of the test tube. It turns red. It indicates that the gas is acidic in nature. When passed into lime water, the lime water turns milky.
One day Reeta went to a jeweller’s shop with her mother. Her mother gave an old gold jewellery to the goldsmith to polish. Next day when they brought the jewellery back, they found that there was a slight loss in its weight. Can you suggest a reason for the loss in weight?
In polishing, the jeweller put the gold jewellery in a mild acidic solution, which on reaction with acid goes into the solution. So, in this process certain amount of gold is lost to the acidic solution.
MP Board Class 8th Science Materials: Metals and Non-Metals NCERT Extended Learning-Activities and Projects
Prepare Index Cards for any four metals and four non-metals. The card should have information like name of metal/non-metal; its physical properties, chemical properties and its uses.
Name of metal: Copper.
(i) It is hard.
(ii) It is ductile and malleable.
(iii) It is a good conductor of heat and electricity.
(i) It reacts, with moist air to form greenish coating.
(ii) It’s oxide is basic in nature.
(iii) It reacts with acids to produce hydrogen gas.
(v) It displaces iron from iron sulphate solution.
Uses: Copper is used to make electrical wires, base of cooking utensils, etc.
Metal and Non-Metal
Name of metal: Zinc
1. It is bluish-white in colour.
2. It is lustrous.
3. It is a reasonable conductor of electricity chemical properties.
(i) It reacts with air and a coating of zinc oxide is formed.
(ii) Zinc does not react with nitrogen,
(iii) In reactions with alkalis, the element forms complex compounds.
Uses: Zinc is used for treatment and prevention of Zinc deficiency and its consequences.
Name of metal: Lead.
1. It is bluish-white lustrous metal.
2. It is a poor conductor of electricity.
3. It is very soft, highly malleable and ductile.
(i) It is a moderately active metal.
(ii) It dissolves slowly in water and in most cold acids.
(iii) It does not react with oxygen in the air readily.
Uses: It is used in ammunition (shot and bullets) and as a constituent of solder.
Name of metal: Iron
(i) It is malleable
(ii) It is ductile
(iii) It is sonorous
(iv) It is hard
(v) It is a good conductor of heat and – electricity.
(i) It reacts with oxygen to form rust.
(ii) It reacts with water.
(iii) It reacts with acid to form hydrogen gas.
Name of non-metal: Coal Physical Properties
(i) It is not ductile.
(ii) It is not malleable.
(iii) It is poor conductor of electricity.
(iv) It is not sonorous and does not shine. It is soft.
(i) It’s oxide is acidic in nature.
(ii) It produces oxides of carbon when burnt.
(iii) It does not take part in replacement reaction.
Uses: Coal is used for electricity generation, cement manufacturing, etc.
Name of non-metal: Sulphur.
(i) It is soft and dull.
(ii) It is neither ductile nor malleable.
(iii) It is a poor conductor of heat and electricity.
(i) It reacts with oxygen to produce sulphur dioxide.
(ii) It reacts with water to form sulphuric acid (H2SO4) which is acidic in nature.
(iii) Metals are heated to mould them.
Uses: Sulphur is used in the vulcanisation of black rubber, fungicide, and in black gunpowder.
Name of non-metal: Aluminium
1. It is a soft metal.
2. It is silvery light metal.
3. It possesses good thermal and electrical conductivity.
1. It reacts strongly with hydrochloric acid and caustic soda.
2. It reacts with oxygen to form aluminium oxide.
Uses: Aluminium is used in a huge variety of products including cans, foils, kitchen utensils, window frames, beer kegs reacts with sodium hydroxide to and aeroplane parts. produce hydrogen gas.
Name of non-metal: Oxygen
Uses: Used to make machines, tools, doors, etc.
1. Oxygen gas is colourless, odourless and colourless.
2. Oxygen exists as liquid, solid and gas.
3. Its elemental structure is a cubic crystal shape.
1. It is a highly reactive element.
2. It supports combustion.
3. It is highly paramagnetic.
Uses: Oxygen gas is used for oxy-acetylene welding and cutting of metals.
Visit a blacksmith and observe how metals are moulded.
Suggest an experiment to compare the conductivity of electricity by iron, copper, aluminium and zinc. Perform the experiment and ^prepare a short report on the results.
Find out the locations of the deposits of iron, aluminium and zinc in India. Mark these in an outline map of India. In which form are the deposits found? Discuss in the class.
Discuss with your parents/neighbours!goldsmiths why gold is preferred for making jewellery.
Gold is preferred for making jewellery because it is less reactive, ductile and is a expensive metal.
MP Board Class 8th Science Materials: Metals and Non-Metals NCERT Intext and Projects Activities
TABLE 4.2 Malleability of Materials
TABLE 4 3 Electrical Conductivity of Materials
MP Board Class 8th Science Materials: Metals and Non-Metals NCERT Additional Important Questions
A. Short Answer Type Questions
Which property of metal is used for making bells?
Metals are generally sonorous. They make a ringing sound when struck. This property of metals is used for making bells.
Why electric wires are made of aluminium and copper?
Electric wires are made of aluminium and copper because they are good conductors of electricity.
Why cooking utensils and water boilers are made of iron, copper and aluminium?
Iron, copper and aluminum have high melting point and they are good conductor of heat. That is why they are used for making utensils and boilers.
What do you understand by ductility?
Metals like copper, aluminium, iron and magnesium can be drawn into wires.
Name a common metal which is highly resistant to corrosion?
The common metal which is highly resistant to corrosion is gold.
B. Long Answer Type Questions
A copper plate was dipped in AgN03 solution. After certain time silver from the solution was deposited on the copper plate. State the reason why it happened? Give the chemical equation of the reaction involved.
Copper is more reactive than silver. Therefore, it displaces silver from silver nitrate.
What are alloy steels? Name any three alloy steels and give their composition.
Steel is an alloy of carbon and iron. When other metals are also present, then it is known as alloy steels. The examples of alloy steel are:
- Stainless steel: Fe + C + Cr + Ni
- Tungsten steel: Fe + C + W
- Iron steel: Fe + C + Ni
Describe some of the physical properties of metals.
General physical properties of metals are:
- Metals have a shiny appearance that is why they show metallic lustre.
- Metals on being hammered can be beaten into thin sheets. This property is called malleability.
- Metals can be drawn into wires. This property is called ductility.
- Metal have high melting point.
- Metals are sonorous that means when struck make a ringing sound.
- They are good conductor of electricity and heat.
Write a short note on:
(a) Galvanizing. It is a common method of protecting iron from rusting. This is done by dipping the object in molten zinc. The metal object get galvanized by zinc.
(b) Electroplating. This is done by coating the object with a layer of tin or chromium with the help of electricity.
(c) Alloying. Metals which corrode easily are mixed with other metals in molten state. A homogenous mixture is made, that mixture is called alloy. So by alloying corrosion is prevented. For example, stainless steel which is an alloy of iron.