Chemistry

Question 1

1In Zn + CuSO₄ → ZnSO₄ + Cu, zinc is

Easy

A. unchanged B. reduced C. a catalyst D. oxidised

Question 2

2Balance: Cr₂O₇²⁻ + Fe²⁺ → Cr³⁺ + Fe³⁺ (acid). The mole ratio Cr₂O₇²⁻ : Fe²⁺ is

Hard

A. 1 : 3 B. 1 : 6 C. 2 : 3 D. 1 : 2

Question 3

3Rusting of iron is an example of

Easy

A. hydrolysis B. neutralisation C. reduction D. oxidation

Question 4

4In MnO₄⁻ + 8H⁺ + 5e⁻ → Mn²⁺ + 4H₂O, the change in oxidation number of Mn is

Hard

A. +6 to +2 B. +7 to +4 C. +7 to +2 D. +4 to +2

Question 5

5In the reaction CuO + H₂ → Cu + H₂O, the reducing agent is

Easy

A. copper B. hydrogen C. copper(II) oxide D. water

Question 6

6Oxidation is

Easy

A. gain of hydrogen B. loss of electrons C. loss of oxygen D. gain of electrons

Question 7

7The oxidation number of sulphur in H₂SO₄ is

Easy

A. +6 B. −2 C. +2 D. +4

Question 8

8Which is the best oxidising agent?

Medium

A. fluorine B. sodium C. zinc D. hydrogen

Question 9

9In electrolysis, reduction takes place at the

Easy

A. cathode B. anode C. salt bridge D. voltmeter

Question 10

10What is the oxidation number of sulphur in H₂SO₄?

Medium

A. +6 B. −2 C. +4 D. +2