Question

Question 31
Although metals form basic oxides, which of the following metals form an amphoteric oxide?
a) $\text{Na}$
(b) $\text{Ca}$
(c) $\text{Al}$
(d) $\text{Cu}$

Answer 1

Option (c) is correct.
Oxides of few metals, such as aluminium, zinc, lead, etc., are amphoteric in nature. This means that these react with both acids as well as bases to produce respective salts and water.

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