April 10, 2026
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Chapter 3: Metals and Non-metals
Complete NCERT Solutions (Intext + Exercise) | CBSE Class 10 Science
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Class 10 (CBSE) - SYLLABUS
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Intext Questions (Page 40)
Q12 marks
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.
(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 (Hg)
(ii) Sodium (Na) or Potassium (K)
(iii) Silver (Ag)
(iv) Lead (Pb) or Mercury
(i) Mercury (Hg)
(ii) Sodium (Na) or Potassium (K)
(iii) Silver (Ag)
(iv) Lead (Pb) or Mercury
Q21 mark
Explain the meanings of malleable and ductile.
Answer:
Malleable: The property of metals by which they can be beaten into thin sheets. Example: Gold, Iron.
Ductile: The property of metals by which they can be drawn into thin wires. Example: Copper, Silver.
Malleable: The property of metals by which they can be beaten into thin sheets. Example: Gold, Iron.
Ductile: The property of metals by which they can be drawn into thin wires. Example: Copper, Silver.
Q32 marks
Why is sodium kept immersed in kerosene oil?
Answer: Sodium is a highly reactive metal. It reacts vigorously with oxygen and moisture present in air. To prevent it from catching fire or reacting with air, it is stored under kerosene oil.
Q43 marks
Write equations for the reactions of
(i) iron with steam
(ii) calcium and potassium with water
(i) iron with steam
(ii) calcium and potassium with water
Answer:
(i)
(ii)
(i)
3Fe(s) + 4H₂O(g) → Fe₃O₄(s) + 4H₂(g)(ii)
Ca(s) + 2H₂O(l) → Ca(OH)₂(aq) + H₂(g)2K(s) + 2H₂O(l) → 2KOH(aq) + H₂(g) (Potassium reacts violently and catches fire)Q53 marks
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 to answer the following questions:
(i) Which is the most reactive metal?
(ii) What would you observe when 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.
| Metal | Iron(II) sulphate | Copper(II) sulphate | Zinc sulphate | Silver nitrate |
|---|---|---|---|---|
| A | No reaction | Displacement | No reaction | Displacement |
| B | Displacement | Displacement | No reaction | Displacement |
| C | No reaction | No reaction | No reaction | Displacement |
| D | No reaction | No reaction | No reaction | No reaction |
(i) Which is the most reactive metal?
(ii) What would you observe when 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 is the most reactive (it displaces iron, copper and silver).
(ii) The blue colour of copper(II) sulphate fades and reddish-brown copper metal is deposited.
(iii) Decreasing order: B > A > C > D
(i) Metal B is the most reactive (it displaces iron, copper and silver).
(ii) The blue colour of copper(II) sulphate fades and reddish-brown copper metal is deposited.
(iii) Decreasing order: B > A > C > D
Q61 mark
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 (H₂) is produced.
Fe(s) + H₂SO₄(aq) → FeSO₄(aq) + H₂(g)Q72 marks
What would you observe when zinc is added to a solution of iron(II) sulphate? Write the chemical reaction that takes place.
Answer: The green colour of iron(II) sulphate fades and grey iron metal is deposited.
Zn(s) + FeSO₄(aq) → ZnSO₄(aq) + Fe(s) Intext Questions (Page 46)
Q85 marks
(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?
(ii) Show the formation of Na₂O and MgO by the transfer of electrons.
(iii) What are the ions present in these compounds?
Answer:
(i) Na (one dot), O (six dots), Mg (two dots).
(ii) Na₂O: 2Na → 2Na⁺ + 2e⁻ ; O + 2e⁻ → O²⁻ ; MgO: Mg → Mg²⁺ + 2e⁻ ; O + 2e⁻ → O²⁻.
(iii) Na₂O has Na⁺ and O²⁻; MgO has Mg²⁺ and O²⁻.
(i) Na (one dot), O (six dots), Mg (two dots).
(ii) Na₂O: 2Na → 2Na⁺ + 2e⁻ ; O + 2e⁻ → O²⁻ ; MgO: Mg → Mg²⁺ + 2e⁻ ; O + 2e⁻ → O²⁻.
(iii) Na₂O has Na⁺ and O²⁻; MgO has Mg²⁺ and O²⁻.
Q92 marks
Why do ionic compounds have high melting points?
Answer: Ionic compounds consist of positive and negative ions held together by strong electrostatic forces. A large amount of energy is needed to break these forces, resulting in high melting points.
NCERT Exercise Questions (Page 56)
Ex 11 mark
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.
(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 is more reactive than silver, so it displaces silver.
Ex 21 mark
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.
(a) applying grease
(b) applying paint
(c) applying a coating of zinc
(d) all of the above.
Answer: (d) all of the above. However, for a frying pan, zinc coating (galvanisation) is most practical.
Ex 31 mark
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.
(a) calcium
(b) carbon
(c) silicon
(d) iron.
Answer: (a) calcium. CaO has a high melting point and reacts with water to form Ca(OH)₂.
Ex 41 mark
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.
(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. Zinc would react with food acids, making the food unsafe.
Ex 53 marks
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.
(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) Hammer test: metals are malleable (beaten into sheets), non-metals are brittle. Electrical test: set up a circuit with the sample; if bulb glows, it's a metal (conductor).
(b) Useful for preliminary distinction, but some non-metals like graphite conduct electricity, so confirm with chemical tests.
(b) Useful for preliminary distinction, but some non-metals like graphite conduct electricity, so confirm with chemical tests.
Ex 62 marks
What are amphoteric oxides? Give two examples of amphoteric oxides.
Answer: Amphoteric oxides are metal oxides that react with both acids and bases to form salt and water. Examples: Aluminium oxide (Al₂O₃), Zinc oxide (ZnO).
Ex 72 marks
Name two metals which will displace hydrogen from dilute acids, and two metals which will not.
Answer: Displace hydrogen: Magnesium (Mg), Zinc (Zn). Do not displace: Copper (Cu), Silver (Ag).
Ex 83 marks
In the electrolytic refining of a metal M, what would you take as the anode, the cathode and the electrolyte?
Answer: Anode: Impure metal M. Cathode: Pure thin strip of metal M. Electrolyte: Soluble salt of metal M (e.g., CuSO₄ for copper).
Ex 93 marks
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. What will be the action of gas on
(i) dry litmus paper?
(ii) moist litmus paper?
Write a balanced chemical equation for the reaction taking place.
(i) dry litmus paper?
(ii) moist litmus paper?
Write a balanced chemical equation for the reaction taking place.
Answer: The gas is sulphur dioxide (SO₂). (i) Dry litmus: No change. (ii) Moist litmus: Turns red (acidic).
S(s) + O₂(g) → SO₂(g)Ex 102 marks
State two ways to prevent the rusting of iron.
Answer: (i) Galvanisation (coating with zinc). (ii) Painting or greasing.
Ex 111 mark
What type of oxides are formed when non-metals combine with oxygen?
Answer: Acidic oxides (e.g., CO₂, SO₂).
Ex 125 marks
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 of metals.
(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 of metals.
Answer: (a) They are less reactive, lustrous, malleable, and ductile.
(b) They are highly reactive with air and moisture; oil prevents reaction and fire.
(c) Aluminium forms a thin, protective layer of aluminium oxide (Al₂O₃) that prevents further corrosion.
(d) It is easier to reduce metal oxides to metals than to reduce carbonates or sulphides. Calcination/roasting converts them to oxides.
(b) They are highly reactive with air and moisture; oil prevents reaction and fire.
(c) Aluminium forms a thin, protective layer of aluminium oxide (Al₂O₃) that prevents further corrosion.
(d) It is easier to reduce metal oxides to metals than to reduce carbonates or sulphides. Calcination/roasting converts them to oxides.
Ex 132 marks
Why does common salt (sodium chloride) have a high melting point?
Answer: It is an ionic compound with strong electrostatic forces between Na⁺ and Cl⁻ ions, requiring high energy to overcome.
Ex 143 marks
Explain the extraction of mercury from its ore cinnabar (HgS). Write the chemical equations involved.
Answer: Roasting:
Then mercury(II) oxide is heated:
2HgS(s) + 3O₂(g) → 2HgO(s) + 2SO₂(g)Then mercury(II) oxide is heated:
2HgO(s) → 2Hg(l) + O₂(g)Ex 152 marks
What happens when a copper coin is dipped in a silver nitrate solution? Give the chemical equation.
Answer: The solution turns blue and shiny silver metal deposits on the coin.
Cu(s) + 2AgNO₃(aq) → Cu(NO₃)₂(aq) + 2Ag(s)Ex 163 marks
What happens when zinc oxide reacts with
(i) hydrochloric acid (HCl)
(ii) sodium hydroxide (NaOH)?
Write chemical equations. What name is given to such reactions?
(i) hydrochloric acid (HCl)
(ii) sodium hydroxide (NaOH)?
Write chemical equations. What name is given to such reactions?
Answer: (i)
(ii)
Such reactions are called amphoteric (ZnO is an amphoteric oxide).
ZnO + 2HCl → ZnCl₂ + H₂O(ii)
ZnO + 2NaOH → Na₂ZnO₂ + H₂OSuch reactions are called amphoteric (ZnO is an amphoteric oxide).
Additional Important Question
Extra2 marks
Name the metal used in thermite welding and the oxide involved. Write the reaction.
Aluminium (Al) and iron(III) oxide (Fe₂O₃).
Fe₂O₃ + 2Al → Al₂O₃ + 2Fe (thermite reaction).Study materials
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