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Answers of Science NCERT solutions for class 10 Chapter 3 Metals & Non-Metals

Chapter 3

Metals & Non-Metals

Question 1:

Give an example of a metal which

  1. is a liquid at room temperature.
  2. can be easily cut with a knife.
  3. is the best conductor of heat.
  4. is a poor conductor of heat.

Answer

  1. Metal that exists in liquid state at room temperature → Mercury
  2. Metal that can be easily cut with a knife → Sodium
  3. Metal that is the best conductor of heat → Silver
  4. Metals that are poor conductors of heat → Mercury and lead

Question 2:

Explain the meanings of malleable and ductile. 

Answer

Malleable: Substances that can be beaten into thin sheets are called malleable. For example, most of the metals are malleable.

Ductile: Substances that can be drawn into thin wires are called ductile. For example, most of the metals are ductile.

Question 1:

Define the following terms.

(i) Mineral (ii) Ore (iii) Gangue 

Answer

  1. Mineral: Most of the elements occur in nature in combined state as minerals. The chemical composition of minerals is fixed.
  2. Ore: Minerals from which metals can be extracted profitably are known as ores.
  3. Gangue: The impurities (sand, silt, soil, gravel, etc.) present in the ore are called gangue.

Question 2:

Write equations for the reactions of

  1. iron with steam
  2. calcium and potassium with water WWerw2UTfgfxlV5TJIPbiup4NCXgNnwUHmk0TMM4fe8NAfiiW6DhZ3Y1HjQDzlo3cHfLAIjXYmo0z5JrN2U9aW4orroLQW2ONigRwY8ybZLiIfwQqlXmIE08rggDKd1yDfMFrdV72CDjnBefXlr3mhttLIG4lnRvmV2GCp5QGIiclA0

Answer

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.

MetalIron (II) sulphateCooper (II) sulphateZinc sulphateSilver nitrate
A.No reactionDisplacement
B.DisplacementNo reaction
C.No reactionNo reactionNo reactionDisplacement
D.No reactionNo reactionNo reactionNo reaction

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

  1. Which is the most reactive metal?
  2. What would you observe if B is added to a solution of copper (II) sulphate?
  3. Arrange the metals A, B, C and D in the order of decreasing reactivity. 

Answer

Explanation

A + FeSO4 → No reaction, i.e., A is less reactive than iron

A + CuSO4 → Displacement, i.e., A is more reactive than copper 

B + FeSO4 → Displacement, i.e., B is more reactive than iron

B + ZnSO4 → No reaction, i.e., B is less reactive than zinc 

C + FeSO4 → No reaction, i.e., C is less reactive than iron

C + CuSO4 → No reaction, i.e., C is less reactive than copper 

C + ZnSO4 → No reaction, i.e., C is less reactive than zinc

C + AgNO3 → Displacement, i.e., C is more reactive than silver

D + FeSO4/CuSO4/ZnSO4/AgNO3 → No reaction, i.e., D is less reactive than iron, copper, zinc, and silver

From the above equations, we obtain:
PzypTC0sMOHeZWOmWaXvAl yE QWC5pCZAQnUIb37GinlZsHW6lRsnn VeeTWMLSTAoO4e2 s6Nj4SidKAe1W3sNJDUaHR5H7YMh15su W ztpy1r9iiEYrZajH4v6fuNQWFRaQ

  1. B is the most reactive metal.
  2. If B is added to a solution of copper (II) sulphate, then it would displace copper.

B + CuSO4 → Displacement

  1. The  arrangement  of  the  metals  in  the  order  of  decreasing  reactivity  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

Hydrogen gas is evolved when dilute hydrochloric acid is added to a reactive metal. When iron reacts with dilute H2SO4, iron (II) sulphate with the evolution of hydrogen gas is formed.IHM4Zs9BE0e8HoPEfrfCv wB3rr9 5cidDjNl mrZuDm6Pt aVpnb4LUTw5D0ETRukrMFGLPsPLUaU 23UmcdHL265veED6UsozHfVZCu3p Jm3ZSTW80w

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

Zinc is more reactive than iron. Therefore, if zinc is added to a solution of iron (II) sulphate, then it would displace iron from the solution.
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Question 1:

  1. Write the electron-dot structures for sodium, oxygen and magnesium.
  2. Show the formation of Na2O and MgO by the transfer of electrons.
  3. What are the ions present in these compounds?

Answer

(i) The representation of elements with valence electrons as dots around the elements is referred to as electron-dot structure for elements.

(ii)iS8frmtQni m U6PbTbAtjWIczbdgeD8vvnT nAXkrFaunwXQ2QEh0LGddYdbU 3wDkAxao3AXavpxgFCve55zNroJH4R 422uuHeQRI97akfZ89mvOVUKGEmAK0NrMqjznfcPc

iBrh5OHtONQzhkvz78zaRvIqouo7sI 1iW jw 8xg lj1 XrDb 4SYoU7LcOjKPAObbroLhXDMGClxI5V9gieO0p2wkaCswfoWU2kSfTh4QK4bWigVg Aszmw i0JcqiBXHRyI

(iii) The ions present in Na2O are Na+ and O2− ions and in MgO are Mg2+ and O2− ions.

Question 2:

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

Answer

The metals at the bottom of the reactivity series are mostly found in free state. For example: gold, silver, and platinum.

Question 3:

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

Answer

The chemical process used for obtaining a metal from its oxide is reduction. In this process, metal oxides are reduced by using suitable reducing agents such as carbon or by highly reactive metals to displace the metals from their oxides.

For example, zinc oxide is reduced to metallic zinc by heating with carbon.
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Manganese dioxide is reduced to manganese by treating it with aluminium powder. In this case, aluminium displaces manganese from its oxide.HsuedFAw2Ofcr RtuzBeAReNPGk2N44q9cPHUIqIksvr2bHM9PXXtpTHtS1IlXxciYY8OLv49eQO418VmhC2C HxkcnoNLIM546VO1D4hdCUpRdQR5oSKrhve VydzSRcJ2kc4c

Oxides of more reactive metals are reduced by electrolysis.

Question 1:

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

MetalZincMagnesiumCopper
Zinc oxide
Magnesium oxide
Copper oxide

In which cases will you find displacement reactions taking place?

Answer

MetalZincMagnesiumCopper
Zinc oxideNo reactionDisplacementNo reaction
Magnesium oxideNo reactionNo reactionNo reaction
Copper oxideDisplacementDisplacementNo reaction

Question 2:

Which metals do not corrode easily? 

Answer

More reactive a metal is, more likely it is to be corroded. Therefore, less reactive metals are less likely to get corroded. This is why gold plating provides high resistance to corrosion.

Question 3:

What are alloys? 

Answer

Alloys are homogeneous mixtures of two or more elements. The elements could be two metals, or a metal and a non-metal. An alloy is formed by first melting the metal and then dissolving the other elements in it. For example, steel is an alloy of iron and  carbon.

Question 1:

Which of the following pairs will give displacement reactions?

  1. NaCl solution and copper metal
  2. MgCl2 solution and aluminium metal
  3. FeSO4 solution and silver metal
  4. AgNO3 solution and copper metal.

Answer

(d) AgNO3 solution and copper metal

Question 2:

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

  1. Applying grease
  2. Applying paint
  3. Applying a coating of zinc
  4. all of the above.

Answer

(c) Applying a coating of zinc

(We can also apply grease and paint to prevent iron from rusting. However, in case of iron frying pan, grease and paint cannot be applied because when the pan will be heated and washed again and again, the coating of grease and paint would get destroyed.)

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

  1. calcium
  2. carbon
  3. silicon
  4. iron 

Answer

(a) The element is likely to be calcium.

Question 4:

Food cans are coated with tin and not with zinc because

  1. zinc is costlier than tin.
  2. zinc has a higher melting point than tin.
  3. zinc is more reactive than tin.
  4. zinc is less reactive than tin.

Answer

(c) Food cans are coated with tin and not with zinc because zinc is more reactive than tin.

Question 5:

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

  1. How could you use them to distinguish between samples of metals and non- metals?
  2. Assess the usefulness of these tests in distinguishing between metals and non- metals.

Answer

  1. With the hammer, we can beat the sample and if it can be beaten into thin sheets (that is, it is malleable), then it is a metal otherwise a non-metal. Similarly, we can use the battery, bulb, wires, and a switch to set up a circuit with the sample. If the sample conducts electricity, then it is a metal otherwise a non-metal.
  2. The above tests are useful in distinguishing between metals and non-metals as these are based on the physical properties. No chemical reactions are involved in these tests.

Question 6:

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

Answer

Those oxides that behave as both acidic and basic oxides are called amphoteric oxides. Examples: aluminium oxide (Al2O3), zinc oxide (ZnO)

Question 7:

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

Answer

Metals that are more reactive than hydrogen displace it from dilute acids. For example: sodium and potassium. Metals that are less reactive than hydrogen do not displace it. For example: copper and silver.

Question 8:

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

Answer

In the electrolytic refining of a metal M:

Anode → Impure metal M

Cathode → Thin strip of pure metal M

Electrolyte → Solution of salt of the metal M

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 figure below.

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  1. What will be the action of gas on
  1. dry litmus paper?
  2. moist litmus paper?
  3. Write a balanced chemical equation for the reaction taking place.

Answer

(a) (i) There will be no action on dry litmus paper.

(ii) Since the gas is sulphur dioxide (SO2), it turns moist blue litmus paper to red because sulphur dioxide reacts with moisture to form sulphurous acid.

(b)
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Question 10:

State two ways to prevent the rusting of iron. 

Answer

Two ways to prevent the rusting of iron are:

  1. Oiling, greasing, or painting: By applying oil, grease, or paint, the surface becomes water proof and the moisture and oxygen present in the air cannot come into direct contact with iron. Hence, rusting is prevented.
  2. Galvanisation: An iron article is coated with a layer of zinc metal, which prevents the iron to come in contact with oxygen and moisture. Hence, rusting is prevented.

Question 11:

What type of oxides is formed when non-metals combine with oxygen? 

Answer

Non-metals combine with oxygen to form acidic oxides. For example:
i9 rNWaEWh4dBNT41MjPjH7LbH5suBOSVaUjyph jkTidQH1Fe L9sYF2

Question 12:

Give reasons

  1. Platinum, gold and silver are used to make jewellery.
  2. Sodium, potassium and lithium are stored under oil.
  3. Aluminium is a highly reactive metal, yet it is used to make utensils for cooking.
  4. Carbonate and sulphide ores are usually converted into oxides during the process of extraction.

Answer

  1. Platinum, gold, and silver are used to make jewellery because they are very lustrous. Also, they are very less reactive and do not corrode easily.
  2. Sodium, potassium, and lithium are very reactive metals and react very vigorously with air as well as water. Therefore, they are kept immersed in kerosene oil in order to prevent their contact with air and moisture.
  3. Though aluminium is a highly reactive metal, it is resistant to corrosion. This is because aluminium reacts with oxygen present in air to form a thin layer of aluminium oxide. This oxide layer is very stable and prevents further reaction of aluminium with oxygen. Also, it is light in weight and a good conductor of heat. Hence, it is used to  make cooking utensils.
  4. Carbonate and sulphide ores are usually converted into oxides during the process of extraction because metals can be easily extracted from their oxides rather than from their carbonates and sulphides.

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

Copper reacts with moist carbon dioxide in air to form copper carbonate and as a result, copper vessel loses its shiny brown surface forming a green layer of copper carbonate. The citric acid present in the lemon or tamarind neutralises the basis copper carbonate and dissolves the layer. That is why, tarnished copper vessels are cleaned with lemon or tamarind juice to give the surface of the copper vessel its characteristic lustre.

Question 14:

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

MetalNon-metal
Metals are electropositive.Non-metals are electronegative.
They react with oxygen to form basic oxides.
These have ionic bonds.
They react with oxygen to form acidic or neutral oxides.These have covalent bonds.
They react with water to form oxides and hydroxides. Some metals react with cold water, some with hot water, and some with steam.
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They do not react with water.
They react with dilute acids to form a salt and evolve hydrogen gas. However, Cu, Ag, Au, Pt, Hg do not react.
1rTrv7cENxC4qFPEajg6QucbeD3R1iLrL45XLTlPWsY7OwXZ mxew7J
They do not react with dilute acids. These are not capable of replacing hydrogen.
They react with the salt solution of metals. Depending on their reactivity, displacement reaction can occur.
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These react with the salt solution of non-metals.
They act as reducing agents (as they can easily lose electrons).
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These act as oxidising agents (as they can gain electrons).
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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 retreat. Can you play the detective to find out the nature of the solution he had used?

Answer

He must have dipped the gold metal in the solution of aqua regia − a 3:1 mixture of conc. HCl and conc. HNO3. Aqua regia is a fuming, highly corrosive liquid. It dissolves gold in it. After dipping the gold ornaments in aqua regia, the outer layer of gold gets dissolved and the inner shiny layer appears. That is why the weight of gold ornament reduced.

Question 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 cold water, hot water, or steam. However, iron reacts with 

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steam. If the hot water tanks are made of steel (an alloy of iron), then iron would react vigorously with the steam formed from hot water.

That is why copper is used to make hot water tanks, and not steel.

Question 1:

Why is sodium kept immersed in kerosene oil? 

Answer

Sodium and potassium are very reactive metals and and combine explosively with air as well as water. Hence, they catch fire if kept in open. Therefore, to prevent accidental fires and accidents, sodium is stored immersed in kerosene oil.

Question 2:

Why do ionic compounds have high melting points? 

Answer

Ionic compounds have strong electrostatic forces of attraction between the ions. Therefore, it requires a lot of energy to overcome these forces. That is why ionic compounds have high melting points.

Access Answers of Science NCERT class 10 Chapter 3 Metals and Non-metals ( All In text and Exercise Questions Solved)

In-text questions set 1 Page number 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?

Solution:

(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.

2. Explain the meanings of malleable and ductile.

Solution:

  1. Metals which can be beaten to sheets are said to be malleable
  2. Metals which can be drawn into thin wires are said to be ductile

In-text questions set 2 Page number 46

1. Why is sodium kept immersed in kerosene oil?

Solution: Sodium is a reactive metals, if kept open it will react with oxygen to explore and catch fire. Sodium metal is kept immersed in kerosene to prevent their reaction with oxygen, moisture and carbon dioxide of air.

2. Write equations for the reactions of

(i) iron with steam

(ii) calcium and potassium with water

Solution: (i) Iron reacts with steam to form a magnetic oxide of Fe with the liberation of H2.

3Fe(s) + 4H2O(g) → Fe3O4(s) + 4H2(g)

(ii) Calcium reacts with water to form calcium hydroxide and hydrogen.

Ca(s) + 2H2O(I) → Ca(OH)2(aq) + H2(g)

Potassium reacts with cold water violently immediately with evolution of H2 which catches fire.

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

MetalIron(II) sulphateCopper(II) sulphateZinc sulphateSilver Nitrate
ANo reactionDisplacement
BDisplacement
CNo reactionNo reactionNo reactionDisplacement
DNo reactionNo reactionNo reactionNo reaction

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

  1. Which is the most reactive metal?
  2. What would you observe if B is added to a solution of Copper (II) sulphate?
  3. Arrange the metals A, B, C and D in the order of decreasing reactivity.

Solution:

(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.

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.

Solution: Hydrogen gas is liberated when dilute HCl is added to a reactive metal.

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.

Solution: 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)

In-text questions set 3 Page number 49

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

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

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

Solution: (i) Sodium:

Na

Oxygen:

o

(ii) Formation of Magnesium oxide:

When magnesium reacts with oxygen, the magnesium atom transfers its two outermost electrons to an oxygen atom. By losing two electrons, the magnesium atoms form a magnesium ion (Mg2+) and by gaining two electrons, the oxygen atom forms an oxide ion (O2-).

Mg:  +
o→ MgO

Formation of Sodium oxide:

Two sodium atoms transfer their 2 outermost electrons to an oxygen atom. By losing two electrons, the two sodium atoms form sodium ions (2Na+). And by gaining two electrons, the oxygen atom forms an oxide ion (O2-).

zz

(iii) The ions present in sodium oxide compound (Na2O) are sodium ions (2Na+) and oxide ions (O2-).

The ions present in Magnesium oxide compound (MgO) are magnesium ions Mg2+ and oxide ions (O2-).

2. Why do ionic compounds have high melting points?

Solution: 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 set 4 Page number 53

1. Define the following terms.

(i) Mineral

(ii) Ore

(iii) Gangue

Solution:

  1. Minerals are compounds (also known as elements) which are found naturally in the earth’s crust. E.g. Alums, K2SO4.Al2(SO4)3.24H2O, etc.
  2. Ores are minerals from which metal can be extracted Ex: Bauxite Al2O3.2H2O is the ore of Al, copper pyrite CuFeS2.All minerals are not considered as ores but all ores are also minerals.
  3. Ores mined from the earth are naturally contaminated with sand, rocky materials. There are impurities present in the ore which are known as gangue.

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

Solution: Gold and platinum are the two metals found in Free State in nature.

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

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

In-text questions set 5 Page number 55

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

MetalZincMagnesiumCopper
Zinc Oxide
Magnesium Oxide
Copper Oxide

Solution:

A more reactive metal can displace a less reactive metal from its oxide. Among Zinc, Magnesium, and Copper metals, magnesium is the most reactive, copper is the least reactive metal and zinc is less reactive .The displacement reaction will take place in the following cases

MetalZincMagnesiumCopper
Zinc OxideDisplacement
Magnesium Oxide
Copper OxideDisplacementDisplacement

2. Which metals do not corrode easily?

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

3. What are alloys?

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

Exercise questions Page number 56-57

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

Solution: 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)

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

  1. Applying grease
  2. Applying paint
  3. Applying a coating of zinc
  4. All of the above

Solution: 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.

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

Solution: 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.

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.

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

Solution:

  1. Metals are malleable and can be easily drown into sheets by hitting with hammer. On the other hand if we beat non-metals they break down and they cannot be drawn into sheets as they are non-malleable. Metals of good conductors of electricity hence they make bulb when you connect metals with a battery, wire and bulb. Similarly If non-metals are bad conductors of electricity chance they fail to lit up the bulb on connecting with wire and battery.
  2. These experiments can be helpful to demonstrate the malleability and electric conductivity of the metals and non-metals

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

Solution: 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.

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

Solution: Zinc (Zn) and Magnesium (Mg) are the two metals which will displace Hydrogen from dilute acids as they are very reactive metals. Gold (Au) and Silver (Ag) are the metals which will not replace Hydrogen from dilute acids as these metals are less reactive.

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

Solution: 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.

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.

Solution: 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

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

Solution:

  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.

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

Solution: 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.

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

Solution:

(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.

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.

Solution: 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.

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

Solution:

MetalsNon-metals
When metals are heated with oxygen, they form ionic oxides which are basic in nature and form bases on dissolving with water. This turn red litmus paper to blue.When non-Metals are heated with oxygen, they form covalent oxides which are acidic in nature which form acid on dissolving with water. This turn blue litmus paper to red.
They are electro positive, lose electrons readily and become a positive ion.They are electro negative, gain electrons and become negative ions.
Metals are lustrous.Non-metals are non-lustrous; graphite is the exception
Reducing agents.Good oxidizing agents.
Metals are the good conductors of electricity and heat.Non-metals are non-conductors of electricity and heat; graphite is the exception
All metals are solids except mercury.Non-metals are in solid-liquid and gaseous states

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?

Solution: 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.

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

Solution: Copper is used to make hot water tanks and not steel (an alloy of iron) because copper does not reacts with either water or steam whereas iron reacts with steams to corrode the tank.


NCERT Solutions for class 10 Science Chapter 3- Metals and Non-metals

Elements can be categorised into two types viz, non-metals and metals. Excluding mercury, all metals are solid at room temperature. Some other important properties of metals include

  • They are malleable
  • Lustrous
  • Good conductors of electricity and heat
  • They lose their electrons to form positively charged ions
  • They form basic oxides by combining with oxygen

What are amphoteric oxides?

Oxides which show basic and acidic properties are called amphoteric oxides. Examples are, zinc oxide and aluminium oxide.

What is metallurgy?

The process of extracting metal from ore and refining it is called metallurgy.

What is corrosion?

Corrosion is a phenomenon where a metal like iron is exposed to moistened air for a long period.

What are non-metals?

Non-metals are not ductile and malleable. Excluding graphite, all non-metals are bad conductors of electricity and heat. They gain electrons to form negative ions when they react with metals. Non-metals form hydrides by reacting with hydrogen. They can form oxides which are either neutral or acidic.

Key Features of NCERT Solutions for Class 10 Science Chapter 3 Metals and Non-metals

  • The information provided in these NCERT Solutions for Class 10 Science Chapter 3 – Metals and Non-metals is authentic and easy to understand.
  • These solutions provide answers to all the exercise questions present at the end of Chapter 3 Metals and Non-metals from NCERT Class 10 Science textbook.
  • The solutions to questions asked in between the chapter have also been provided.
  • NCERT Solutions for Class 10 Science Chapter 3 Metals and Non-metals are provided by SWC subject experts only after extensive research.
  • These solutions will be useful for various competitive exams such as JEE, NEET, etc.
  • Students can rely on these solutions to prepare for their board exam as it consists of tips, shortcuts, step by step procedure and neat labelled diagrams to tackle the complex type of questions smartly.

Frequently Asked Questions on NCERT Solutions for Class 10 Science Chapter 3

List out the differences between metals and non metals based on their physical properties in Chapter 3 of NCERT Solutions for Class 10 Science.

The differences between metals and non metals based on their physical properties are –
1. All metals are solid at room temperature except mercury whereas the non-metals can be in solid, liquid or gas form.
2. Metals are lustrous whereas non metals are non lustrous.
3. Metals possess high density whereas non metals possess low density.
4. Metals are good conductors of heat and electricity whereas non metals are poor conductors.
5. Metals have high melting point whereas non metals have low melting and boiling point.

Mention the uses of metals and non metals explained in the Chapter 3 of NCERT Solutions for Class 10 Science.

Metals are used in electronic equipment like mobiles, TV, fridges etc. Medicines for nerve impulses, enzyme reaction and oxygen carriers make use of metals. Micronutrient metal deficiency diseases in animals and humans can also be cured by using some metals. Non metals are used as an important ingredient in chemical solutions, powerful disinfectant and as an important element in combustion in batteries.


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NCERT Solutions Class 10 Science Chapters

  • Chapter 1 Chemical Reaction and equation
  • Chapter 2 Acid, Base and Salts
  • Chapter 3 Metals & Non-Metals
  • Chapter 4 Carbon and its Compounds
  • Chapter 5 Periodic Classification of Elements
  • Chapter 6 Life Processes
  • Chapter 7 Control and Coordination
  • Chapter 8 How do Organisms Reproduce
  • Chapter 9 Heridity
  • Chapter 10 Light, Reflection & Refraction
  • Chapter 11 Human Eye
  • Chapter 12 Electricity
  • Chapter 13 Magnetic effects of electric current
  • Chapter 14 Sources of Energy
  • Chapter 15 Environment

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