On dilution,the $pH$ of $CH_3COONH_4$ solution:

Consider the following aqueous solutions:
$(1)$ $FeCl_3$ is basic
$(2)$ $NH_4Cl$ is acidic
$(3)$ $NaCN$ is acidic
$(4)$ $Na_2CO_3$ is basic
Which of the following statements is $NOT$ correct?

Which of the following solutions has the maximum $pH$ value?

The solution of $Na_2CO_3$ has $pH$:

$A$ $100 \ L$ solution of $KCN$ undergoes $3.7\%$ hydrolysis. If the dissociation constant of $HCN$ is $7.2 \times 10^{-10}$,find the value of $K_w$.

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