WAEC Chemistry 2014 Paper

Concept:Aqueous $\mathrm{Na}_2\mathrm{CO}_3$ is a salt formed from a weak acid and a strong base; its hydrolysis produces a basic solution.Explanation:When dissolved in water, the carbonate ion reacts with water.$$\mathrm{CO}_3^{2-} + \mathrm{H}_2\mathrm{O} \rightleftharpoons \mathrm{HCO}_3^- + \mathrm{OH}^-$$This equilibrium releases hydroxide ions, $\mathrm{OH}^-$, into the solution.The presence of excess $\mathrm{OH}^-$ makes the solution basic or alkaline with pH greater than 7.Hence, an aqueous solution of $\mathrm{Na}_2\mathrm{CO}_3$ is not acidic, neutral, or amphoteric.Answer:B. alkaline