Explain acidity of bases with example.

Show by the help of an appropriate litmus paper that the aqueous solution of ammonia is alkaline in nature. 

What is an alkali? Do basic solutions also have ${\mathrm{H}}^{+}$(aq) ions? If yes, then why are these basic? 

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

If $\mathrm{pH}$ of a solution is 13, means that it is

Explain the alkali.

The $\mathrm{pH}$ of a compound is found to be 9. The compound can be