Question

Which of the following metals form amphoteric oxide?

• A. Copper
• B. Silver
• C. Aluminium
• D. Iron

Answer 1

The correct option is C Aluminium

Aluminium forms amphoteric oxides since it reacts with both acids and bases.
Aluminium on reaction with oxygen form alumina which shows both acidic as well as basic behaviours and react with both acids and bases to produce salts and water. Such metal oxides are known as amphoteric oxides.
An example is given below:
${\text{Al}}_2{O}_3\left(s\right)+6\text{HCl}\left(aq\right)\to 2{\text{AlCl}}_3\left(aq\right)+{\text{3H}}_2\text{O}\left(l\right)$
[Acidic nature]

${\text{Al}}_2{O}_3\left(s\right)+2\text{NaOH}\left(aq\right)\to 2{\text{NaAlO}}_2\left(aq\right)+{\text{H}}_2\text{O}\left(l\right)$
[Basic nature]