What is the $pH$ of a $2 \times 10^{-3} \ M$ solution of a monoacidic weak base if it ionizes to the extent of $5 \%$?

If the ionization constant of hypochlorous acid $(HOCl)$ is $2.5 \times 10^{-5}$,the $pH$ of $1.0 \ M$ of its solution is $(\log 5=0.7)$.

The degree of dissociation of $0.1 \, M \, HCN$ solution is $0.01 \%$. Its ionisation constant would be

$A$ monoprotic acid in a $0.1 \ M$ solution ionizes to $0.001 \%$. Its ionisation constant is

$A$ weak monobasic acid is $20 \%$ dissociated in its $0.01 \ M$ solution. What is the dissociation constant of the weak acid?

The first and second ionization constants of $H_2X$ are $2.5 \times 10^{-8}$ and $1.0 \times 10^{-13}$ respectively. The concentration of $X^{2-}$ in $0.1 \ M$ $H_2X$ solution is . . . . . . $\times 10^{-15} \ M$. The value of $Y$ is: