Zinc oxide is treated with sodium hydroxide solution. The product will be

Name the following:

A base that is amphoteric in nature. 

The reagent used to distinguish between $\mathrm{Fe}(\mathrm{OH}{)}_3$ and $\mathrm{Al}(\mathrm{OH}{)}_3$

Name the following:

An oxide, which forms salts when it reacts both with acids and alkalis. 

Name the following:

A white metal oxide that dissolves when fused with caustic soda but soluble in excess of ammonium hydroxide.