Question

The salt which will give an acidic solution on dissolving in water is:
(a) KCl
(b) NH₄Cl
(c) Na₂Co₃
(d) CH₃COONa

Answer 1

 NH₄Cl 
NH₄Cl is formed with a weak base, ammonium hydroxide (NH₄OH), and a strong acid, hydrochloric acid (HCl). On dissolving in water, NH₄Cl hydrolyses to form more H⁺ ions than OH^- ions. Thus, it is acidic with a pH less than 7.