Concept:An amphoteric substance can react with both acids and bases.
Explanation:Zinc oxide,
ZnO, is classified as amphoteric because it shows acidic as well as basic behaviour.
It reacts with an acid to form a salt and water.
It also reacts with a base to form a salt and water.
This dual reactivity proves that
ZnO can act as both a basic oxide and an acidic oxide.
Therefore, the property of reacting with either a base or an acid defines its amphoteric nature.
Answer:D. reacts with a base or an acid