Class X Science Multiple Choice Questions For Chemistry Ch-1 Chemical Reactions and Equations

1. The chemical formula of lead sulphate is

(a) Pb₂ SO₄

(b) Pb(SO₄)₂

© PbSO₄

(d) Pb₂ (SO₄)₃

2. 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

© Number of atoms/molecules of the reactants and products formed

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

3. Chemically rust is

(a) hydrated ferrous oxide

(b) only ferric oxide

© hydrated ferric oxide

(d) none of these

4. Both CO₂ and H₂ gases are

(a) heavier than air

(b) colourless

© acidic in nature

(d) soluble in water

5. Which of the following gases can be used for storage of fresh sampel of an oil for a long time?

(a) Carbon dioxide or oxygen

(b) Nitrogen or helium

© Helium or oxygen

(d) Nitrogen or oxygen

6. The electrolytic decomposition of water gives H₂ and O₂ in the ratio of

(a) 1 : 2 by volume

(b) 2 : 1 by volume

© 8 : 1 by mass

(d) 1 : 2 by mass

7. In the decomposition of lead (II) nitrate to give lead (II) oxide, nitrogen dioxide and oxygen gas, the coefficient of nitrogen dioxide (in the balanced equation) is

(a) 1

(b) 2

© 3

(d) 4

8. Fatty foods become rancid due to the process of

(a) oxidation

(b) corrosion

© reduction

(d) hydrogenation

9. We store silver chloride in a dark coloured bottle because it is

(a) a white solid

(b) undergoes redoc reaction

© to avoid action by sunlight

(d) none of the above

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

(a) H₂ S

(b) AgS

© AgSO₄

(d) Ag₂ S

11. When crystals of lead nitrate are heated strongly in a dry test tube

(a) crystals immediately melt

(b) a brown residue is left

© white fumes appear in the tube

(d) a yellow residue is left

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

(a) The surface of metal becomes shining

(b) The reaction mixture turns milky

© Odour of a pungent smelling gas is recorded

(d) A colourless and odourless gas is evolved

13. When carbon dioxide is passed through lime water,

(a) calcium hydroxide is formed

(b) white precipitate of CaO is formed

© lime water turns milky

(d) colour of lime water disappears.

14. When a magnesium ribbon is burnt in air, the ash formed is

(a) black

(b) white

© yellow

(d) pink

15. In which of the following, heat energy will be evolved?

(a) Electrolysis of water

(b) Dissolution of NH4Cl in water

© Burning of L.P.G.

(d) Decomposition of AgBr in the presence of sunlight

16. Rancidity can be prevented by

(a) adding antioxidants

(b) storing food away from light

© keeping food in refrigerator

(d) all of these

17. The reaction of H₂ gas with oxygen gas to form water is an example of

(a) combination reaction

(b) redox reaction

© exothermic reaction

(d) all of these reactions

18. The reaction in which two compound exchange their ions to form two new compounds is called

(a) displacement reaction

(b) combination reaction

© double displacement reaction

(d) redox reaction

19. On immersing an iron nail in CuSO₄ solution for few minutes, you will observe

(a) no reaction takes place

(b) the colour of solution fades away

© the surface of iron nails acquire a black coating

(d) the colour of solution changes to green

20. An element X on exposure to moist air turns reddish-brown and a new compound Y is formed. The substance X and Y are

(a) X = Fe, Y = Fe₂ O₃

(b) X = Ag, Y = Ag₂ S

© X = Cu, Y = CuO

(d) X = Al, Y = Al₂ O₃

Answers