Rohit has three solutions X , Y and Z that have pH 2, 7 and 13 respectively. Which solution out of X , Y or Z will:

(a) X

Reason — Sodium sulphite reacts with an acid to liberate sulphur dioxide gas. Hence, solution X with pH 2 is acidic and will liberate sulphur dioxide.

SO₃^2- + 2H⁺ ⟶ SO₂ + H₂O

(b) Z

Reason — Ammonium salts liberate ammonia gas on reaction with an alkali. Hence, solution Z with pH 13 is alkaline and will liberate ammonia from ammonium chloride.

NH₄⁺ + OH^- ⟶ NH₃ + H₂O

(c) Y

Reason — The solution Y with pH 7 will not have any effect on litmus paper as it is neither acidic nor basic.