Which one of the following salts gives an acidic solution in water?

In which of the following salts,only cationic hydrolysis is involved?

An aqueous solution of aluminium sulphate shows

The $pH$ of a $0.01 \, M$ ammonium cyanide $(NH_4CN)$ solution is $7.02$. If $5 \, L$ of water is added to this solution,the $pH$ will be .......

Calculate the $pH$ of a $0.018 \, M$ sodium acetate solution,given its $K_a = 1.8 \times 10^{-5}$. (in $.5$)

Classify salts based on their hydrolysis and provide examples for each category.