Question

Assertion (A): Aluminium oxide is an example of amphoteric oxide.
Reason (R): Aluminium oxide reacts with both acids and bases.

• A. Both A and R are true and R is the correct explanation of A
• B. Both A and R are true but R is not the correct explanation of A
• C. A is true but R is false
• D. A is false but R is true

Answer 1

The correct option is A Both A and R are true and R is the correct explanation of A

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

Reactions of aluminium oxide are as following:

${\text{Al}}_2{O}_3\left(s\right)+6\text{HCl}\left(aq\right)\to 2{\text{AlCl}}_3\left(aq\right)+{\text{3H}}_2\text{O}\left(l\right)$
[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]

Therefore, Both A and R are true and R is the correct explanation of A