JAMB Chemistry 2024 Paper

Concept:Amphoteric oxides react with both acids and bases to form salt and water.Explanation:Consider the reactions of $\mathrm{Al}_2\mathrm{O}_3$.With acid: $\mathrm{Al}_2\mathrm{O}_3 + 6\mathrm{HCl} \rightarrow 2\mathrm{AlCl}_3 + 3\mathrm{H}_2\mathrm{O}$.With base: $\mathrm{Al}_2\mathrm{O}_3 + 2\mathrm{NaOH} \rightarrow 2\mathrm{NaAlO}_2 + \mathrm{H}_2\mathrm{O}$.Because $\mathrm{Al}_2\mathrm{O}_3$ neutralizes both hydrochloric acid and sodium hydroxide, it shows both acidic and basic properties.Other common amphoteric oxides include $\mathrm{ZnO}$ and $\mathrm{PbO}$.Among the options, $\mathrm{P}_4\mathrm{O}_{10}$ is acidic, $\mathrm{CuO}$ is basic, and $\mathrm{K}_2\mathrm{O}$ is strongly basic.Only $\mathrm{Al}_2\mathrm{O}_3$ behaves as an amphoteric oxide.Answer:B. $\mathrm{Al}_2\mathrm{O}_3$