Question

Which of the following metal oxides can react with acids as well as strong alkalies?

• A. ${\mathrm{Ag}}_2\mathrm{O}$
• B. CuO
• C. ${\mathrm{Al}}_2{\mathrm{O}}_3$
• D. CaO

Answer 1

The correct option is C

${\mathrm{Al}}_2{\mathrm{O}}_3$

The correct answer is option c) ${\mathrm{Al}}_2{\mathrm{O}}_3$

Definition of amphoteric oxides and hydroxides.

• The compounds which can react with both acids and alkalis to form salt and water. Such substances are called amphoteric oxides and hydroxides.

Explanation of correct answer

• When aluminium oxide react with sodium hydroxide, Sodium aluminate is formed .

${\mathrm{Al}}_2{{\mathrm{O}}_3}_{\left(\mathrm{s}\right)}+2{\mathrm{NaOH}}_{\left(\mathrm{aq}\right)}\to 2{{\mathrm{NaAlO}}_2}_{\left(\mathrm{aq}\right)}+{\mathrm{H}}_2{\mathrm{O}}_{\left(\mathrm{l}\right)}$

• When aluminium oxide react with Hydrochloric acid, aluminium chloride and water is formed.

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

Explanation of incorrect answer

${\mathrm{Ag}}_2\mathrm{O}$, CuO, CaO they are not amphoteric in nature. So they does not react with acids and alkalis.