NCERT Solutions for Class 10 Science Chapter 3

NCERT Solutions for Class 10 Science Chapter 3 Metals and Non metals, contains solutions to various questions in Exercises for Chapter 3. Metals and Non metals Class 10 NCERT Solutions have been explained in a simple and easy to understand manner. We are providing NCERT Solutions for Class 10 all subjects which can be accessed by clicking here.

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NCERT Solutions for Class 10 Science Chapter 3 – Metals and Non metals – NCERT Exercises

NCERT Solutions for Class 10 Science Chapter 3 – Metals and Non metals, Exercises includes all in text and exercise solved questions which helps you to understand the topic covered in Chapter 3 Metals and Non metals Class 10, in a better manner to help you to score good marks in your examinations.

NCERT Solutions for Class 10 Science Chapter 3 – Intext Questions – Page 40

1. Give an example of a metal which

(i) is a liquid at room temperature.

(ii) can be easily cut with a knife.

(iii) is the best conductor of heat.

(iv) is a poor conductor of heat.

Answer:

(i) Mercury

(ii) Sodium

(iii) Silver

(iv) Mercury

2. Explain the meanings of malleable and ductile.

Answer:

Malleable: If a metal holds the property of being able to beaten into sheets, it is called malleable.

Ductile: If a metal holds the property of being able to drawn into sheets, it is called ductile.

Intext Questions – Page 46

1. Why is sodium kept immersed in kerosene oil?

Answer:

Sodium reacts highly with oxygen at room temperature making it a volatile metal. Hence, it is kept immersed in kerosene.

2. Write equations for the reactions of

(i) iron with steam

 (ii) calcium and potassium with water

Answer:

(i) 3Fe(s) + 4H2O(g) → Fe3O4(s) + 4H2(g)

(ii) Ca(s) + 2H2O(I) → Ca(OH)2(aq) + H2(g)

2K(s) + 2H2O(I) → 2KOH(aq) + 2H2(g)

3. Samples of four metals A, B, C and D were taken and added to the following solution one by one. The results obtained have been tabulated as follows.

Use the Table above to answer the following questions about metals A, B, C and D.

(i) Which is the most reactive metal?

(ii) What would you observe if B is added to a solution of Copper(II) sulphate?

(iii) Arrange the metals A, B, C and D in the order of decreasing reactivity.

Answer:

(i) Metal B

(ii) When metal B is added to copper (II) sulphate solution, a displacement reaction will take place and we observe that the blue colour of copper (II) sulphate solution will fade and a red-brown deposit of copper will be formed on metal B.

(iii) The correct order is:

B > A > C > D

Metal B is the most reactive because it displaces iron from its salt solution.

Metal A is less reactive because it displaces copper from its salt solution.

Metal C is still less reactive because it can displace only silver from its salt solution.

Metal D is the least reactive because it did not displace any metal from its salt solution.




4. Which gas is produced when dilute hydrochloric acid is added to a reactive metal? Write the chemical reaction when iron reacts with dilute H2SO4 .

Answer:

Hydrogen gas is liberated when dilute HCl is added to a reactive metal. The reaction can be given as:

Fe(s) + H2SO4(aq) → FeSO4(aq) + H2(g)

5. What would you observe when zinc is added to a solution of iron(II) sulphate? Write the chemical reaction that takes place.

Answer:

Since zinc is more reactive than iron, we observe that zinc displaces iron from its salt solution and converts the pale green solution into a colorless solution.

FeSO4 + Zn → ZnSO4 + Fe(s)

NCERT Solutions for Class 10 Science Chapter 3 – Intext Questions – Page 49

1. (i) Write the electron-dot structures for sodium, oxygen and magnesium.

(ii) Show the formation of Na2O and MgO by the transfer of electrons.

(iii) What are the ions present in these compounds?

Answer:

(i) Sodium:

Sodium

Oxygen:

Oxygen

Magnesium:

Magnesium

(ii) Formation of Na2O

Oxygen requires two atoms to complete its octet. Two sodium atoms give their outermost single electron and sodium oxide is formed.

Formation of Na2O

Formation of MgO

Magnesium has two electrons in the outermost orbit and they share it with Oxygen to form magnesium oxide.

Formation of MgO

(iii) Sodium oxide has two Na+ ions and one O2-

Magnesium oxide has one Mg2+ and one O2- ions.

2.Why do ionic compounds have high melting points?

Answer:

Heat is required to overcome the forces of attraction. Since ionic compounds have both positive and negative ions, they form a very strong bond of attraction which is difficult to overcome. Hence, ionic compounds have high melting points.

Intext Questions – Page 53

1. Define the following terms.

(i) Mineral
(ii) Ore
(iii) Gangue

Answer:

(i) Mineral: Compounds found naturally in earth’s crust are called minerals. Example: Alums.

(ii) Ore: Ores contain metals. Ores are purified and metals are extracted from them. For example, Magnetite is an iron ore, and Bauxite is an aluminium ore.

(iii) Gangue: The impurities and contaminates present in the ores like sand, etc are called gangue.

 2. Name two metals which are found in nature in the free state.

Answer:

Two metals found in nature in the free state are (i) gold (ii) silver.

3. What chemical process is used for obtaining a metal from its oxide?

Answer:

Reduction is the process of removing oxygen. Reduction is the chemical process used to obtain a metal from its oxide. For example, Lead oxide is reduced to lead by heating it with carbon:

PbO + C ⇒ Pb + CO

NCERT Solutions for Class 10 Science Chapter 3 – Intext Questions – Page 55

1. Metallic oxides of zinc, magnesium and copper were heated with the following metals.

In which cases will you find displacement reactions taking place?

Answer:

If a metal is more reactive than other, it displaces it in its oxide. Reactivity in increasing order is: Copper < Zinc < Magnesium. Following the reactivity series, we can fill the table.




2. Which metals do not corrode easily?

Answer:

Gold and Platinum do not corrode easily.

3. What are alloys?

Answer:

Alloys are homogeneous mixtures of two or more metals, or a metal and a non-metal. For example, steel is an alloy of iron, carbon, and small amounts of other elements like silicon, copper, etc.

NCERT Solutions for Class 10 Science Chapter 3 – NCERT Exercise – Page 56

1. Which of the following pairs will give displacement reactions?

(a) NaCl solution and copper metal

(b) MgCl2 solution and aluminium metal

(c) FeSO4 solution and silver metal

(d) AgNO3 solution and copper metal.

Answer:

(d). AgNO3 solution and copper metal.

Copper displaces silver.

2. Which of the following methods is suitable for preventing an iron frying pan from rusting?

(a) Applying grease

(b) Applying paint

(c) Applying a coating of zinc

(d) All of the above

Answer:

(c) Applying a coating of Zinc.

It is not appropriate to coat frying pans with grease and paint, so zinc is used to coat them to avoid rusting.

3. An element reacts with oxygen to give a compound with a high melting point. This compound is also soluble in water. The element is likely to be

(a) calcium

(b) carbon

(c) silicon

(d) iron

Answer:

(a) Calcium

Calcium reacts with oxygen to give calcium oxide which has a high melting point and is soluble in water.

4. Food cans are coated with tin and not with zinc because

(a) zinc is costlier than tin.

(b) zinc has a higher melting point than tin.

(c) zinc is more reactive than tin.

(d) zinc is less reactive than tin.

Answer:

(c ) zinc is more reactive than tin.

5. You are given a hammer, a battery, a bulb, wires and a switch.

(a) How could you use them to distinguish between samples of metals and non-metals?

(b) Assess the usefulness of these tests in distinguishing between metals and non-metals.

Answer:

(a) We know metals are good conductor of electricity, are malleable and ductile, where as non-mental do not conduct electricity and are break when hit with force. We can use the given things to distinguish metals on the basis of these properties. If we connect the metals with battery and bulb using the wires to form a circuit, the bulb will glow. Similarly, if we beat a metal with a hammer, it will be easy to beat it into sheets whereas a non-metal will break from the force.

(b) These tests can be quite useful in distinguishing the metals and non-metals on the basis of their physical properties.

6. What are amphoteric oxides? Give two examples of amphoteric oxides.

Answer:

Oxides that can react with both acids and bases to give salt and water are called amphoteric oxides. Aluminium oxide (Al2O3) is an amphoteric oxide.

7. Name two metals which will displace hydrogen from dilute acids, and two metals which will not.

Answer:

Two metals which will displace hydrogen from dilute acids are: 1. Magnesium 2. Zinc. (Very reactive in nature.)

Two metals that will not displace hydrogen from dilute acids are: 1. Gold 2. Silver. (Less reactive, noble metals.)

8. In the electrolytic refining of a metal M, what would you take as the anode, the cathode and the electrolyte?

Answer:

In electrolytic refining of metal M, the electrolyte is a solution of suitable salt of metal M, the anode is the block of impure metal M, and the cathode is a thin strip of pure metal M.

9. Pratyush took sulphur powder on a spatula and heated it. He collected the gas evolved by inverting a test tube over it, as shown in figure below.

(a) What will be the action of gas on
(i) dry litmus paper?
(ii) moist litmus paper?
(b) Write a balanced chemical equation for the reaction taking place.

Answer:

(a) The heating of sulphur powder results in formation of sulphur dioxide gas which is collected in test tube.
(i) It will have no effect on dry litmus paper as no acid will be formed.
(ii) After coming in contact with moisture, sulphur dioxide turns into sulfurous acid and turns blue litmus into green.

(b) The reactions involved are:

S(s) + O2(g) → SO2(g)

SO2(g) + H2O(l) →H2SO3(aq)




10. State two ways to prevent the rusting of iron.

Answer:

Two ways to prevent rusting of iron are:

(i) Coating things made from iron with paint and grease.
(ii) Galvanization can be done to apply a zinc coating on the iron.

11. What type of oxides are formed when non-metals combine with oxygen?

Answer:

Either acidic or neutral oxides are formed when non-metals combine with oxygen. For example:

Nitrogen combines with oxygen to form acidic N2O5
Carbon combines with oxygen to from neutral CO.

12. Give reasons

(a) Platinum, gold and silver are used to make jewellery.

(b) Sodium, potassium and lithium are stored under oil.

(c) Aluminium is a highly reactive metal, yet it is used to make utensils for cooking.

(d) Carbonate and sulphide ores are usually converted into oxides during the process of extraction.

Answer:

(a) Since gold and silver are not very reactive, they do not react with the air and water present in the atmosphere and do not lose their shine easily. They last longer. Hence, they are used to make jewellery.

(b) Sodium, potassium and lithium are highly reactive metals, at room temperature, they combine with water present in atmosphere and burn violently. To store them safely, they are kept in oil (usually kerosene).

(c) The surface of aluminium reacts with oxygen in present in atmosphere to form a thin layer of aluminium oxide. This layer of aluminium oxide is very stable and prevents aluminium from reacting any further. Because of this, we can use aluminium to make vessels as it is cheap and a good conductor of electricity.

(d) It is easier to extract metals from their oxides by the methods or roasting and calcination than extracting metals from their carbonates and sulphides. Hence, we convert metals into oxides during the process of extraction.

13. You must have seen tarnished copper vessels being cleaned with lemon or tamarind juice. Explain why these sour substances are effective in cleaning the vessels.

Answer:

Copper reacts with carbon dioxide and moisture present in air to form a greenish layer of copper carbonate (CuCO3.Cu(OH)2). The acids present in these sour substances dissolve this layer, restoring the color and shine of the metal.

14. Differentiate between metal and non-metal on the basis of their chemical properties.

Answer:

The difference between metals and non-metals on the basis of their chemical properties are as given:

metal and non-metal

15. A man went door to door posing as a goldsmith. He promised to bring back the glitter of old and dull gold ornaments. An unsuspecting lady gave a set of gold bangles to him which he dipped in a particular solution. The bangles sparkled like new but their weight was reduced drastically. The lady was upset but after a futile argument the man beat a hasty retreat. Can you play the detective to find out the nature of the solution he had used?

Answer:

The solution used is acidic in nature. Popularly known as Aqua Regia (royal water in Latin), it is mixture of concentrated HCl and concentrated HNO3 in the ration 3:1. It can easily react with noble metals like gold and dissolve their upper layer which results in lesser weight.

16. Give reasons why copper is used to make hot water tanks and not steel (an alloy of iron).

Answer:

Copper does not react with water or steam whereas steel, which contains iron easily reacts with water to form rust and corrodes. So, we use copper to make hot water tanks.




Topics Covered in Metals and Non metals Class 10 Science

  • Physical properties of metals
  • Physical properties of non-metals
  • Chemical Properties of Metals
  • Reactions of Metals and Non-Metals
  • Occurrence of Metals
  • Corrosion
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