set 1 MCQ Questions & Answers Detailed Explanation

Question : 1

Slow eating away of iron articles in the presence of moist air is called

a) rusting

b) galvanisation

c) crystallisation

d) neutralisation

Question : 2

When hydrogen sulphide gas is passed through a blue solution of copper sulphate, a black precipitate of copper sulphide is formed. This is an example of

a) decomposition reaction

b) combination reaction

c) displacement reaction

d) double decomposition reaction

Question : 3

CuO + H₂ ⟶ Cu + H₂O Above reaction is an example of

a) neutralisation reaction

b) Redox reaction

c) synthesis reaction

d) decomposition reaction

Question : 4

The chromate and dicharomate ions are respectively

a) CrO^-₄ and CrO^-₅

b) CrO^2-₄ and Cr₂O^2-₇

c) Cr₂O^2-₇and CrO_4-

d) CrO^2-₄ and Cr₂O^2-₅

Question : 5

$Na_2S_2O_3$ represent the compound

a) sodium thiosulphate

b) sodium sulphate

c) sodium sulphite

d) None of these

Question : 6

Which one is a decomposition reaction ?

a) 2H₂O $⟶ ↖ {Electrolysis}$ 2H₂ + O₂

b) 2HgO $⟶ ↖ {heat}$ 2Hg + O₂

c) CaCO₃ $⟶ ↖ {heat}$ CaO + CO₂

d) All the above reactions are decomposition reaction