NCERT Solutions Class 10 for Science Chapter 3 Metals and Non-Metals

NCERT Solutions Class 10 for Science Chapter 3 Metals and Non-Metals : In this post, we will share with you all the detailed NCERT Solutions of Class 10 Science Chapter 3 Metals and Non-Metals. This will contain both in-text and back-exercise questions for Science and Social Science, and all exercise questions for Mathematics. For all school and board level examinations, doing all the NCERT Questions is a must.

Why are NCERT Questions Important?

NCERT Questions and Answers not only help you get hold of concepts firmly and enhance your understanding, but also form the base of all types of questions asked in exams. Questions asked in exam are more or less the same type as mentioned in NCERT. Moreover, sometimes the questions in NCERT are directly asked in exams, as it is, without any changes.

Hence, it’s very important to understand NCERT Questions and Answers.

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Class 10 Science Chapter 3 – Metals and Non-Metals


In-Text Questions (Page 40)

Question 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 1:
(i) Mercury is the metal which is liquid at room temperature
(ii) Sodium and potassium are the metals which can be cut with a knife
(iii) Silver is the best conductor of heat
(iv) Mercury and lead are poor conductor of heat.

Question 2:
Explain the meanings of malleable and ductile.

Answer 2:
Malleable : A metal that can be beaten into thin sheets on hammering is called malleable.
Ductile : A metal which can be drawn into thin wires is called ductile.

In-Text Questions (Page 46)

Question 1:
Why is sodium kept immersed in kerosene oil ?

Answer 2:
Sodium is highly reactive. So it is kept immersed in kerosene oil to prevent its reaction with oxygen, moisture and carbon dioxide of air to prevent accidental fires.

Question 2:
Write equations for the reactions of
(i) iron with steam.
(ii) calcium and potassium with water.

Answer 2:

Question 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 3:
(i) Metal B is the most reactive as it gives displacement reaction with iron (II) sulphate.
(ii) When metal B is added to copper (II) sulphate solution, a displacement reaction will take place because of which the blue colour of copper (II) sulphate solution will fade and a red-brown deposit of copper will be formed on metal B.
(iii)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 and metal D is the least reactive because it cannot displace any metal from its salt solution. Hence, the decreasing order of reactivity of the metals is B > A > C > D.

Question 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 4:
Hydrogen gas is produced when dilute hydrochloric acid is added to a reactive metal.
Chemical reaction when iron reacts with dilute H2SO4 :
Fe(s) + H2SO4(aq) → FeSO4(aq) + H2(g)

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

Answer 5:
Zinc is more reactive (more electro positive) than iron. Therefore Zinc displaces Iron from its salt solution. The colour of ferrous sulphate is pale green, which turns colourless.
FeSO4 + Zn → ZnSO4 + Fe(s)
Light green     Zinc sulphate(Colourless)

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In-Text Questions (Page 49)

Question 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 ions present in these compounds?

Answer 1:

Question 2:
Why do ionic compounds have high melting points?

Answer 2:
Ionic compounds are the ones which has both positive and negative charges. Hence there will be strong force of attraction between them. This make expenditure of lot of heat to break this force of attraction hence ionic compounds have high melting points.

In-Text Questions (Page 53)

Question 1:
Define the following terms : (i) Mineral, (ii) Ore and (iii) Gangue.

Answer 1:
(i) Mineral : The natural materials in which the metals or their compounds are found in earth are called minerals.
(ii) Ore : Those minerals from which the metals can be extracted conveniently and profitably are called ores.
(iii) Gangue : The unwanted impurities like sand, rocky material, earth particles, lime stone, mica, etc in an ore are called gangue.

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

Answer 2:
Gold and platinum

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

Answer 3:
Reduction method is used to obtain metal from its oxide. Ex: Zinc oxide is reduced to metallic zinc by Heating with carbon.
ZnO + C → Zn + CO
Ex: Lead oxide is reduced to lead by heating with carbon
PbO +C → Pb + CO

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In-Text Questions (Page 55)

Question 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 1:
A more reactive metal can displace a less reactive metal from its oxide. But out of zinc, magnesium, and copper metals, magnesium is the most reactive, zinc is less reactive whereas copper is the least reactive metal.
The displacement will take place in the following cases :

Question 2:
Which metals do not corrode easily ?

Answer 2:
Gold and platinum are the metals which do not corrode easily

Question 3:
What are alloys ?

Answer 3:
An alloy is a homogeneous mixture of two or more metals, or a metal and a non-metal.

Exercise Questions (Page 56-57)

Question 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 1:
Option d i.e AgNO3 solution and copper is correct answer. Copper displace the silver cations (reducing them to the elemental metal), in the process copper itself being oxidised to Copper II cations (Cu2+) and going into solution. So silver metal precipitating out and a copper II nitrate solution will be remaining.
Cu(s) + 2AgNO3 (aq) → Cu(NO3)2 (aq) + 2Ag (s)

Question 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 the above.

Answer 2:
Answer is (c) Applying a coat of Zinc
Though applying grease and applying paint prevents iron from rusting but we cannot apply these methods on frying pan hence applying a coat of Zinc is most appropriate method to prevent an iron pan from rusting.

Question 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 3:
Correct answer is option (a) i.e Calcium.
Calcium reacts with oxygen to give calcium oxide. Calcium oxide is soluble in water to give Calcium Hydroxide.
Carbon forms carbon-oxide with oxygen which is gas hence option B is wrong
Silicon reacts with oxygen and forms silicon dioxide. This is insoluble in water. So option C is not correct.
Iron reacts with oxygen and forms Iron dioxide. This is insoluble in water. So option D is not correct.

Question 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 less reactive than tin
(d) zinc is more reactive than tin.

Answer 4:
Answer is c. Food cans are coated with tin and not with zinc because Zinc is more reactive that is electro positive than tin.

Question 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 5:
(a) Metals can be beaten into thin sheets with a hammer without breaking. Non-metals cannot be beaten with a hammer to form thin sheets. Non-metals break into pieces when hammered. Metals are malleable, while non-metals are non-melleable. When metals are connected into circuit using a battery, bulb, wires and switch, current passes through the circuit and the bulb glows. When non-metals (like sulphur) are connected, the bulb does not light up at all. Metals are good conductors of electricity.
(b) Because of malleability, metals can be casted into sheets. Metals are good conductors of electricity so these can be used for electrical cables.

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Question 6:
What are amphoteric oxides ? Give two examples of amphoteric oxides ?
Write chemical equations that show aluminium oxide reacts with acid as well as base.

Answer 6:
Oxides that react with both acids and bases to form salt and water are known as amphoteric oxides. Examples: PbO and Al2O3.

Amphoteric oxides are the one which reacts with both acids and bases to form salt and water. Examples: Lead oxide – PbO and Aluminium oxide – Al2O3.

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

Answer 7:
(i) Metals above hydrogen in the activity series like sodium and magnesium displace hydrogen from dilute acids.
(ii) Metals below hydrogen in the activity series like copper, silver do not displace hydrogen from dilute acids.

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

Answer 8:
In the process of electrolytic refining of metal called ‘M’, An impure and thick block of metal M. is considered as anode, Thin strip or wire of pure metal M is taken as cathode. A suitable salt solution of metal M is considered as the electrolyte.

Question 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 the figure.
(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 9:
a) When sulphur powder is burnt in the air sulphur-di-oxide is formed.
(i) Sulphur-di-oxide does not have any effect on dry litmus paper.
(ii) Sulphur-di-oxide turn the moist litmus paper from blue to red as contact of SO2 with water turns to sulfurous acid.

(b) S(s) + O2(g) → SO2(g)
SO2(g) + H2O →H2SO3

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

Answer 10:
1.Iron can be prevented from rusting by coating the surface of the iron with rust proof paints
2.By applying Oil/grease on the surface of iron objects as it will prevent the iron surface to get in contact with air consisting of moisture.

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

Answer 11:
When non-metals combine with oxygen it forms either acidic or neutral oxides. Ex: N2O5 or N2O3 is an acidic oxide; CO is a neutral oxide.

Question 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 12:
(a) Platinum, gold and silver are used to make jewellery for these metals are very less reactive hence they are not affected by air, water or most chemicals. These metals have a lot of luster and they are malleable and ductile in nature and also high corrosion resistance in nature.

(b) Sodium, potassium and lithium readily react with water to produce a lot of heat. As a result, Hydrogen evolved in the reaction results in a fire. On exposure to water they react with moisture (water droplets) present in the atmosphere, In order to prevent contact with water hence these metals are stored under oil.

(c) Aluminium forms on its surface a nonreactive surface of aluminium oxide. Such coating prevents other compounds from reacting to aluminium. So aluminium is being used to produce utensils for cooking.

(d) Reducing metal oxide into free metal is easy. Additionally, because it is easier to obtain metals directly from their oxides than from their carbonates or sulphides, the carbonate and sulphide ores are first transformed to oxides to obtain the metals.

Question 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 13:
Tarnished copper vessels being cleaned with lemon or tamarind because this sour substance contains acids which dissolve the coating of copper oxide or basic copper carbonate present on the surface or tarnished copper vessels. This makes them shining red-brown again. Hence they are very effective in cleaning tarnished copper vessels.

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

Answer 14:

Question 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 repeat. Can you play the detective to find out the nature of the solution he has used ?

Answer 15:
Goldsmith used the solution called Aqua regia which is called as royal water in Latin. It is the mixture of concentrated Hydrochloric acid and concentrated nitric acid in the ratio of 3:1. Aqua regia is capable of dissolving noble metals like gold and platinum. When upper-layer of dull gold ornament is dissolved they lose their weight.

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

Answer 16:
(i) Copper is a better conductor of heat than steel.
(ii) Copper does not corrode easily. But steel corrodes easily.
(iii) Copper does not react with water at any temperature, whereas iron reacts with water on heating.


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