Question

Which one of the following is an amphoteric oxide?

• A. ${\mathrm{Na}}_2\mathrm{O}$
• B. ${\mathrm{SO}}_2$
• C. ${\mathrm{B}}_2{\mathrm{O}}_3$
• D. $\mathrm{ZnO}$

Answer 1

The correct option is D

$\mathrm{ZnO}$

Explanation for the correct option

(D) $\mathbf{ZnO}$

Amphoteric Oxides of Metals

• Amphoteric oxides can show both acidic and basic behavior and thus can react with both bases and acids respectively.
• Example: Lead oxide and Aluminium oxide.

$\mathbf{ZnO}$

• $\mathrm{ZnO}$ (Zinc oxide) can react with both acid and base.
• The reaction of $\mathrm{ZnO}$ with hydrochloride acid $\left(\mathrm{HCl}\right)$ is as follows:

$\mathrm{ZnO}\left(\mathrm{s}\right)+2\mathrm{HCl}\left(\mathrm{aq}\right)\to {\mathrm{ZnCl}}_2\left(\mathrm{aq}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$

• The reaction of $\mathrm{ZnO}$ with Sodium hydroxide $\left(\mathrm{NaOH}\right)$ is as follows:

$\mathrm{ZnO}\left(\mathrm{s}\right)+2\mathrm{NaOH}\left(\mathrm{aq}\right)\to {\mathrm{Na}}_2{\mathrm{ZnO}}_2\left(\mathrm{aq}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$

• $\mathrm{ZnO}$ is amphoteric oxide.

Explanation for incorrect options

(A) ${\mathbf{Na}}_{\mathbf{2}}\mathbf{O}$

• ${\mathrm{Na}}_2\mathrm{O}$ (Sodium oxide) is a basic oxide.

(B) ${\mathbf{SO}}_{\mathbf{2}}$

• ${\mathrm{SO}}_2$ (Sulfur dioxide) is acidic oxide.

(C) ${\mathbf{B}}_{\mathbf{2}}{\mathbf{O}}_{\mathbf{3}}$

• ${\mathrm{B}}_2{\mathrm{O}}_3$ (Boron trioxide) is acidic oxide.

Therefore, the correct option is (D) $\mathbf{ZnO}$.