Which pair of compounds are examples of amphoteric oxides?

Amphoteric oxides are oxides that can react with both acids and bases, exhibiting dual behavior depending on the nature of the reacting substance. The correct answer includes chromic oxide (Cr2O3) and vanadium pentoxide (V2O5), both of which exhibit amphoteric properties.

Chromic oxide can react with acids to form chromium salts and can also react with bases to form chromites, showcasing its ability to behave as both an acid and a base. Similarly, vanadium pentoxide can react with strong acids to produce vanadic acid and can also react with strong bases, forming vanadates.

This dual functionality is what defines amphoteric oxides, distinguishing them from other types of oxides. Other options presented contain compounds that do not exhibit such versatility. For instance, sulfur dioxide and phosphorus pentoxide are primarily acidic oxides; sodium oxide and potassium oxide are strongly basic, while magnesium oxide and calcium oxide are primarily basic oxides, thus lacking the characteristics of amphoteric behavior.