Question

Although metals generally form basic oxides, which of the following metals form an amphoteric oxide?

• A. $Na$
• B. $Ca$
• C. $Al$
• D. $Cu$

Answer 1

Answer: (C)

$Al$

Metals in general form basic oxides when they combine with oxygen. In the case of Aluminium, it forms an amphoteric oxide. Amphoteric oxides are metal oxides that can react with both acids as well as alkalis producing salt and water.

The reactions are given below:

$A{l}_2{O}_3+6HCl\to 2AlC{l}_3+3H_{2}O$ (acts as a basic oxide)
$A{l}_2{O}_3+2NaOH\to 2NaAl{O}_2+H_{2}O$ (acts as an acidic oxide)