Question

Which one of the following is an amphoteric oxide? 

Hint:

Amphoteric oxides react with both acids and bases. Examples include \( {ZnO} \), \( {Al}_2{O}_3 \), and \( {Cr}_2{O}_3 \).

Answer 1

Step 1: Definition of Amphoteric Oxide 
An amphoteric oxide is an oxide that can react with both acids and bases to form salt and water. 
Step 2: Identifying \( {Cr}_2{O}_3 \) as an Amphoteric Oxide 
Chromium(III) oxide \( ({Cr}_2{O}_3) \) is an amphoteric oxide because: - It reacts with acids (e.g., \( {HCl} \)) to form \( {CrCl}_3 \): \[ {Cr}_2{O}_3 + 6{HCl} \rightarrow 2{CrCl}_3 + 3{H}_2{O} \] - It reacts with bases (e.g., NaOH) to form chromates: \[ {Cr}_2{O}_3 + 2{NaOH} + 3{H}_2{O} \rightarrow 2{NaCr(OH)}_4 \] 
Step 3: Conclusion 
Since \( {Cr}_2{O}_3 \) can react with both acids and bases, it is classified as an amphoteric oxide.