Question

One of the following salts will give an alkaline solution on dissolving in water. This is:

a) Na₂CO₃
(b) Na₂SO₄
(c) NaCl
(d) (NH₄)₂ SO₄

Answer 1

Na₂CO₃
Na₂CO₃ is formed from a weak acid, carbonic acid (H₂CO₃), and a strong base, sodium hydroxide (NaOH). On dissolving in water, Na₂CO₃ hydrolyses to form more OH^- ions than H⁺ ions. Therefore, its solution in water is basic, or alkaline, with a pH more than 7.