The oxides which can act as an acid or base both are known as the amphoteric oxides. Many metals like zinc, lead, gallium, arsenic are amphoteric oxides. Such type of oxides when reacts with the acid or base. They formed the salt and water. So, the amphoteric oxides are ${\mathrm{Ga}}_2{\mathrm{O}}_3, {\mathrm{As}}_4{\mathrm{O}}_{10}, {\mathrm{Sb}}_4{\mathrm{O}}_{10}$.