The concentration of $[CN^{-}]$ in $0.1 \, M \, HCN$ solution is: $(K_a = 4 \times 10^{-10})$

$HClO$ is a weak acid. The concentration of ${H^+}$ ions in $0.1 \ M$ solution of $HClO$ $(K_a = 5 \times 10^{-8})$ will be equal to:

For a weak acid,the incorrect statement is

The $pH$ of a $0.01 \ M$ weak acid $HX$ $(K_{a}=4 \times 10^{-10})$ is found to be $5$. Now the acid solution is diluted with excess of water so that the $pH$ of the solution changes to $6$. The new concentration of the diluted weak acid is given as $x \times 10^{-4} \ M$. The value of $x$ is $...........$ (nearest integer)

The $pH$ of $0.005 \, M$ codeine $(C_{18}H_{21}NO_{3})$ solution is $9.95$. Calculate its ionization constant and $pK_{b}$.

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