Question

Which of the following oxide is amphoteric in nature

• A. ${\mathrm{Na}}_2\mathrm{O}$
• B. ${\mathrm{Li}}_2\mathrm{O}$
• C. ${\mathrm{K}}_2\mathrm{O}$
• D. $\mathrm{BeO}$

Answer 1

The correct option is D

$\mathrm{BeO}$

Definition for amphoteric oxides:

Amphoteric oxides are metal oxides that react with both acids and bases to generate salts and water.

Explanation for the correct option:

D) Among these oxides, Beryllium oxide $\left(\mathrm{BeO}\right)$ is the only one that reacts with both acids and bases.

Reaction with acid: $\underset{\mathrm{Beryllium}\mathrm{oxide}}{\mathrm{BeO}\left(\mathrm{s}\right)}+\underset{\mathrm{Hydrochloric}\mathrm{acid}}{2\mathrm{HCl}\left(\mathrm{l}\right)}+2\underset{\mathrm{Water}}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}\to \underset{\mathrm{Beryllium}\mathrm{chloride}}{{\mathrm{BeCl}}_2\left(\mathrm{s}\right)}+2\underset{\mathrm{Water}}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}$

Reaction with base: $\underset{\mathrm{Beryllium}\mathrm{oxide}}{\mathrm{BeO}\left(\mathrm{s}\right)}+\underset{\mathrm{Sodium}\mathrm{hydroxide}}{2\mathrm{NaOH}\left(\mathrm{aq}\right)}+2\underset{\mathrm{Water}}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}\to \underset{\mathrm{Sodium}\mathrm{tetrahydroxoberyllate}\left(\mathrm{II}\right)}{{\mathrm{Na}}_2\mathrm{Be}{\left(\mathrm{OH}\right)}_4\left(\mathrm{s}\right)}+2\underset{\mathrm{Water}}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}$

Explanation for the incorrect options

A) Sodium oxide $\left({\mathrm{Na}}_2\mathrm{O}\right)$ is basic oxide since it contains the oxide ion, ${\mathrm{O}}^{2-}$ , which is a highly strong base with a significant attraction for hydrogen ions.

B) Lithium oxide $\left({\mathrm{Li}}_2\mathrm{O}\right)$ is highly basic. Lithium $\left(\mathrm{Li}\right)$ when dissolved in water gives Lithium oxide $\left({\mathrm{Li}}_2\mathrm{O}\right)$ .

C) Potassium oxide $\left({\mathrm{K}}_2\mathrm{O}\right)$ is a basic oxide, as treatment with water gives Potassium oxide $\left({\mathrm{K}}_2\mathrm{O}\right)$.

Hence, option D is the correct answer. Beryllium oxide $\left(\mathrm{BeO}\right)$ is amphoteric in nature.