Question

Metal oxides generally react with acids, but few oxides of metal also react with bases. Such metallic oxides are:

1. MgO
2. ZnO
3. Al₂O₃ 
4. Cao

Options

• I and II

• II and III

• III and IV

• I and IV

Answer 1

II and III

Explanation:

Some metal oxides, such as aluminium oxide, zinc oxide shows both acidic as well as basic behaviour. Such metal oxides that react with both acids and bases to produce salt and water are known as amphoteric oxides.

Aluminium oxide reacts with base as follows:

\[\ce{Al2O3 + 2NaOH -> \underset{(Sodium aluminate)}{2NaAlO2} + H2O}\]

ZnO is an oxide that can react with base, as shown by the equation given below:

\[\ce{ZnO + 2NaoH -> Na2ZnO2 + H2O}\]