Oxides of zinc and aluminium are _____ in nature. 

The salt solution which does not react with ammonium hydroxide is:

What are amphoteric oxides? Give an example.

The metals which can form amphoteric oxides with oxygen are:

Write down the changes that will be seen in each instance and explain the reason behind it.

Zinc oxide was added to dilute $\mathrm{HCl}$ and zinc oxide was added to dilute $\mathrm{NaOH}$.