Question

The salt whose aqueous solution will have no effect on either red litmus or blue litmus is
(a) potassium sulphate
(b) sodium carbonate
(c) ammonium sulphate
(d) sodium acetate

Answer 1

a) potassium sulphate

Potassium sulphate (K₂SO₄) is formed from a strong acid, sulphuric acid (H₂SO₄), and a strong base, potassium hydroxide (KOH). On dissolving in water, K₂SO₄ hydrolyses to form equal amounts of H⁺ and OH^- ions. As the salt solution of K₂SO₄ is neutral, it has no effect on red or blue litmus paper.