Question

Which of the following oxides is amphoteric?

• A. $MgO$
• B. $P_2{O}_5$
• C. $S{O}_3$
• D. $A{l}_2{O}_3$

Answer 1

The correct option is D $A{l}_2{O}_3$

$A{l}_2{O}_3$ can act as either an acid or a base in a reaction to produce salt. Hence, it is called as an amphoteric oxide.

With acid:
$A{l}_2{O}_3+6HCl\to 2AlC{l}_3+3H_{2}O$

With base:
$A{l}_2{O}_3+2NaOH+3H_{2}O\to 2NaAl(OH{)}_4$

$MgO$ is basic in nature.
$P_2{O}_5$ and $S{O}_3$ are acidic in nature.