Question

Which of the following is an example of an amphoteric oxide?

• A. ${\mathrm{SO}}_2$
• B. ${\mathrm{P}}_2{\mathrm{O}}_5$
• C. $\mathrm{BaO}$
• D. $\mathrm{ZnO}$

Answer 1

The correct option is D

$\mathrm{ZnO}$

Explanation for correct option:

D. $\mathrm{ZnO}$

Amphoteric oxide:

• The oxides that exhibit the properties of both acidic as well as basic characteristics are known as Amphoteric oxides.
• Amphoteric oxides form salts when they react with acid and they also react with bases to form complex salts.
• Examples of Amphoteric oxides are Aluminum$\left({\mathrm{Al}}_2{\mathrm{O}}_3\right)$ oxide as well as Zinc oxide $\left(\mathrm{ZnO}\right)$.

Zinc oxide reactions with acid and base:

• Zinc oxide is an amphoteric oxide that can react with both acid as well as a base.

Reaction of Zinc oxide with $\mathrm{HCl}$:

• When Zinc oxide $\left(\mathrm{ZnO}\right)$ reacts with $\mathrm{HCl}$, it forms Zinc chloride $\left({\mathrm{ZnCl}}_2\right)$ and water.
• The chemical equation can be depicted as:

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

Reaction of Zinc oxide with $\mathrm{NaOH}$:

• When Zinc oxide $\left(\mathrm{ZnO}\right)$ reacts with sodium hydroxide $\left(\mathrm{NaOH}\right)$, it forms sodium zincate $\left({\mathrm{Na}}_2{\mathrm{ZnO}}_2\right)$ and water.
• The chemical equation can be depicted as:

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

Explanation for inorrect options:

A: Sulfur dioxide $\left({\mathrm{SO}}_2\right)$is an acidic oxide.

B: Phosphorus pentaoxide $\left({\mathrm{P}}_2{\mathrm{O}}_5\right)$ is an acidic oxide.

C: Barium oxide $\left(\mathrm{BaO}\right)$ is a basic oxide.

Hence, the correct option is D i.e. Zinc oxide $\left(\mathrm{ZnO}\right)$.