Question

The oxide which can react with HCl as well as KOH to give corresponding salt and water is

• A. CuO
• B. Al2O3
• C. Na2O
• D. K2O

Answer 1

Answer: (B)

Al2O3

Answer 2

Al$_2$O$_3$ is an amphoteric oxide, which reacts with both acids and bases:
$\text{Al}_2\text{O}_3 + 6\text{HCl} \rightarrow 2\text{AlCl}_3 + 3\text{H}_2\text{O}.$
$\text{Al}_2\text{O}_3 + 2\text{KOH} + 3\text{H}_2\text{O} \rightarrow 2\text{K[Al(OH)}_4].$
This property makes it unique among the given options.