Question

Q2. A white insoluble oxide that dissolves when fused with caustic soda or caustic potash

• A. Aluminium Sulphate
• B. Aluminium hydroxide
• C. Aluminium Nitrate
• D. Aluminium oxide

Answer 1

The correct option is D

Aluminium oxide

• The reaction of Aluminium oxide with caustic soda $\mathrm{NaOH}$ is:

$\underset{\mathrm{Aluminium}\mathrm{oxide}}{{\mathrm{Al}}_2{\mathrm{O}}_3}+\underset{\mathrm{sodium}\mathrm{hydroxide}}{2\mathrm{NaOH}}\to +\underset{\mathrm{water}}{{\mathrm{H}}_2\mathrm{O}}+\underset{\mathrm{sodium}\mathrm{aluminate}}{2{\mathrm{NaAlO}}_2}$

• Hence option D is correct. Aluminium Oxide is the white insoluble oxide that dissolves when fused with caustic soda or caustic potash.