CBSE Class 10 Chemistry MCQs Set A

Question :  The electrolytic decomposition of water gives H₂ and O₂ in the ratio of

a) 2 : 1 by volume

b) 1 : 2 by volume

c) 8 : 1 by mass

d) 1 : 2 by mass

Answer :  2 : 1 by volume

Question :  Methane on combustion gives

a) both CO₂ & H₂O

b) CO₂

c) H₂O

d) neither CO₂ nor H₂O

Answer :  both CO₂ & H₂O

Question :  Which of the following gases can be used for storage of fresh sample of an oil for a long time?

a) Nitrogen or helium

b) Carbon dioxide or oxygen

c) Helium or oxygen

d) Nitrogen or oxygen

Answer :  Nitrogen or helium

Question :  Both CO₂ and H₂ gases are

a) Colourless

b) Heavier than air

c) Acidic in nature

d) Soluble in water

Answer :  Colourless

Question :  Which of the following are exothermic processes?

(i) Evaporation of water

(ii) Dilution of an acid (H₂SO₄)

(iii) Reaction of water with quick lime

(iv) Sublimation of camphor (crystals)

a) (ii) & (iii)

b) (i) & (ii)

c) (iii) & (iv)

d) (i) & (iv)

Answer :  (ii) & (iii)

Question :  Chemically rust is:

a) Hydrated ferric oxide

b) Hydrated ferrous oxide

c) Only ferric oxide

d) None of these

Answer :  Hydrated ferric oxide

Question :  Which information is not conveyed by a balanced chemical equation?

a) Physical states of reactants and products

b) Symbols and formulae of all the substances involved in a particular reaction.

c) Number of atoms/molecules of the reactants and products formed.

d) Whether a particular reaction is actually feasible or not.

Answer :  Physical states of reactants and products

Question :  In the reaction, SO₂ (g) + 2H₂S (g) -> 2H₂(g) + S(s), the reducing agent is

a) H₂S

b) SO₂ 

c) H₂O

d) S

Answer :  H₂S

Question :  The chemical formula of lead sulphate is

a) PbSO₄

b) Pb₂SO₄

c) Pb(SO₄)₂

d) Pb₂(SO₄)₃

Answer :  PbSO₄

Question :  10g of hydrogen is burnt in the presence of excess oxygen. The mass of water formed is

a) 18g

b) 90g

c) 45g

d) 10g

Answer :  18g

Question :  Identify the following type of reaction 2KClO₃ Heat -> Catalyst 2KCl (s) + 3O₂(g)

a) It is a decomposition reaction and is endothermic in nature

b) It is a combination reaction

c) It is a decomposition reaction and is accompanied by release of heat

d) It is a photochemical decomposition reaction and exothermic in nature

Answer :  It is a decomposition reaction and is endothermic in nature

Question :  When carbon dioxide is passed through lime water,

a) White milkiness is noticed

b) Calcium hydroxide is formed

c) White precipitate of CaO is formed

d) Colour of lime water disappears

Answer :  White milkiness is noticed

Question :  Dilute hydrochloric acid is added to granulated zinc taken in a test tube. The following observations are recorded. Point out the correct observation

a) A colourless and odourless gas is evolved

b) The surface of metal becomes shining

c) The reaction mixture turns milky

d) Odour of a pungent smelling gas is recorded

Answer :  A colourless and odourless gas is evolved

Question :  Which of the following will be required to identify the gas evolved when dilute hydrochloric acid reacts with zinc metal?

a) A burning splinter

b) Lime water

c) Red litmus paper

d) Ph paper

Answer :  A burning splinter

Question :  When crystals of lead nitrate are heated strongly in a dry test tube

a) A brown residue is left

b) Crystals immediately melt

c) White fumes appear in the tube

d) A yellow residue is life

Answer :  A brown residue is left

Question :  Silver article turns black when kept in the open for a few days due to formation of

a) Ag₂S

b) H₂S

c) AgS

d) AgSO_⁴

Answer :  Ag₂S

Question :  We store silver chloride in a dark coloured bottle because it is

a) To avoid action by sunlight

b) A white solid

c) Undergoes redox reaction

d) None of the above

Answer :  To avoid action by sunlight

Question :  Fatty foods become rancid due to the process of

a) Oxidation

b) Corrosion

c) Reduction

d) Hydrogenation

Answer :  Oxidation

Question : Which of the following reaction is used in white washing walls?

a) Ca(OH)₂ + CO₂ ->CaCO₃ + H₂O

b) 2Ca + O₂ -> 2CaO

c) CaO + H₂O -> Ca (OH)₂

d) Ca(OH)₂ + CO₂ -> CalO₃ + H₂O

Answer : Ca(OH)₂ + CO₂ ->CaCO₃ + H₂O

Question :  Reddish-brown copper metal forms a black solid on combustion. Which of the following statement is incorrect?

a) Black solid is CuO

b) The reaction is a redox reaction

c) The reaction is a precipitation reaction

d) Copper is being oxidised

Answer :  Black solid is CuO

Question :  The electrolytic decomposition of water gives H2 and O2 in the ratio of

a) 2 : 1 by volume

b) 1 : 2 by volume

c) 8 : 1 by mass

d) 1 : 2 by mass

Answer :  2 : 1 by volume

Question :  Methane on combustion gives

a) both CO₂ & H₂O

b)  CO₂

c) H₂O

d) neither CO₂ nor H₂O

Answer :  both CO₂ & H₂O

Question :  Which of the following gases can be used for storage of fresh sample of an oil for a long time?

a) Nitrogen or helium

b) Carbon dioxide or oxygen

c) Helium or oxygen

d) Nitrogen or oxygen

Answer :  Nitrogen or helium

Question :  Both CO₂ and H₂ gases are

a) Colourless

b) Heavier than air

c) Acidic in nature

d) Soluble in water

Answer :  Colourless

Question :  Which of the following are exothermic processes?

(i) Evaporation of water (ii) Dilution of an acid (H₂SO₄) (iii) Reaction of water with quick lime (iv) Sublimation of camphor (crystals)

a) (ii) & (iii)

b) (i) & (ii)

c) (iii) & (iv)

d) (i) & (iv)

Answer :  (ii) & (iii)

Question :  Chemically rust is:

a) Hydrated ferric oxide

b) Hydrated ferrous oxide

c) Only ferric oxide

d) None of these

Answer :  Hydrated ferric oxide

Question :  Which information is not conveyed by a balanced chemical equation?

a) Physical states of reactants and products

b) Symbols and formulae of all the substances involved in a particular reaction.

c) Number of atoms/molecules of the reactants and products formed.

d) Whether a particular reaction is actually feasible or not.

Answer :  Physical states of reactants and products

Question :  In the reaction, SO₂ (g) + 2H₂S (g) -> 2H₂(g) + S(s), the reducing agent is

a) H₂S

b) SO₂

c) H₂O

d) S

Answer :  H₂S

Question :  The chemical formula of lead sulphate is

a) PbSO₄

b) Pb₂SO₄

c) Pb(SO₄)₂

d) Pb₂(SO₄)₃

Answer :  PbSO₄

Question :  10g of hydrogen is burnt in the presence of excess oxygen. The mass of water formed is

a) 18g

b) 90g

c) 45g

d) 10g

Answer :  18g