Question

is a metal which reacts with oxygen gas to form an amphoteric oxide.

• A. Potassium
• B. Calcium
• C. Aluminium

Answer 1

The correct option is C Aluminium

Aluminium on reaction with oxygen forms alumina which shows both acidic as well as basic behaviours and reacts with both acids and bases to produce salts and water. Such metal oxides are known as amphoteric oxides.

For example, the reaction of aluminium with an acid and a base is:

$A{l}_2{O}_3+6HCl\to 2AlC{l}_3+3H_{2}O$
$A{l}_2{O}_3+2NaOH\to 2NaAl{O}_2+H_{2}O$