What are amphoteric oxides? Give two examples of amphoteric oxides?

Amphoteric oxides are oxides of metals which have both acidic as well as basic behaviour. Such metallic oxides react with acids as well as a base to produce salt and water. It can accept or donate the proton or H⁺ ion therefore appearing as an acid or a base. 

 Examples of Amphoteric oxides are aluminum oxide(Al₂O₃) and zinc oxide(ZnO).

 

In base: $\ ZnO\ +\ 2\ NaOH\ +\ H_{2} O\rightarrow \ Na_{2}[ Zn( OH)_{4}]$

          Zinc Oxide + Sodium Hydroxide--> Sodium Zinc Hydroxide

In acid: $ZnO\ +\ H_{2} SO_{4}\rightarrow \ ZnSO_{4} +\ H_{2} O$

      Zinc Oxide + Sulphuric Acid --> Zinc Sulphate + Water