Class 10 CBSE Science – Chapter 1 | MCQ Test (Set -5)

11 mark(s)

A student heats 10 g of calcium carbonate in a closed container. After complete decomposition, which statement is correct? CaCO3 → CaO + CO2

ATotal mass of products is less than 10 g.BTotal mass of products is more than 10 g.CTotal mass of products is exactly 10 g.DMass of calcium oxide is 10 g.

21 mark(s)

When copper powder is heated in air, it turns black. The black substance is treated with hydrogen gas and turns reddish-brown again. Which statement is correct?

ACopper is reduced in both reactions.BCopper is oxidised first and reduced later.CCopper is oxidised in both reactions.DCopper is reduced first and oxidised later.

31 mark(s)

A student mixes aqueous solutions of lead nitrate and potassium iodide. A yellow precipitate forms. The remaining solution contains:

AOnly lead nitrateBLead iodideCOnly potassium iodideDPotassium nitrate

41 mark(s)

Which of the following reactions involves oxidation and reduction simultaneously?

ACuO + H2 → Cu + H2OB2Pb(NO3)2 → 2PbO + 4NO2 + O2CZn + 2HCl → ZnCl2 + H2DCaO + H2O → Ca(OH)2

51 mark(s)

A metal X is placed in a blue solution of copper sulphate. After some time, the solution becomes colourless and a reddish-brown deposit forms. Metal X could be:

ASilverBGoldCZincDCopper

61 mark(s)

In the reaction Fe2O3 + 2Al → Al2O3 + 2Fe, which substance acts as the reducing agent?

AAluminiumBIron(III) oxideCIronDAluminium oxide

71 mark(s)

Three students perform the following experiments: Student A: Keeps silver chloride in sunlight. Student B: Heats ferrous sulphate crystals. Student C: Passes electric current through water. Which students are performing decomposition reactions?

AOnly ABOnly B and CCOnly A and BDA, B and C

81 mark(s)

Chips packed with nitrogen gas remain fresh for a longer time. What is the main reason?

ANitrogen reacts with oil to form antioxidants.BNitrogen prevents contact of oils and fats with oxygen.CNitrogen increases moisture content.DNitrogen increases the rate of oxidation.

91 mark(s)

Consider the reaction: 2AgBr → 2Ag + Br2 (in sunlight) Which statement is correct?

ASilver is oxidised and bromine is reduced.BSilver is reduced and bromide ions are oxidised.CBoth silver and bromine are oxidised.DNo redox reaction occurs.

101 mark(s)

A student adds dilute hydrochloric acid to sodium carbonate. The gas evolved is passed through lime water, which turns milky. Which conclusion is correct?

AHydrogen gas is evolved and forms calcium hydroxide.BOxygen gas is evolved and forms calcium oxide.CCarbon dioxide is evolved and forms insoluble calcium carbonate.DNitrogen dioxide is evolved and forms calcium nitrate.