A weak acid $HA$ has a $K_a$ of $1.00 \times 10^{-5} $. If $0.100\,mol$ of this acid is dissolved in one litre of water the percentage of acid dissociated at equilibrium is closest to.....$\%$

Dimethyl amine ${\left( {C{H_3}} \right)_2}NH$ is weak base and its ionization constant $ 5.4 \times {10^{ - 5}}$. Calculate $\left[ {O{H^ - }} \right],\left[ {{H_3}O} \right]$, $pOH$ and $pH$ of its $0.2$ $M$ solution at equilibrium.

The dissociation constant of a substituted benzoic acid at $25^{\circ} \mathrm{C}$ is $1.0 \times 10^{-4}$. The $\mathrm{pH}$ of a $0.01 \ \mathrm{M}$ solution of its sodium salt is

Given

$(i)$ $\begin{gathered}
  HCN\left( {aq} \right) + {H_2}O\left( l \right) \rightleftharpoons {H_3}{O^ + }\left( {aq} \right) + C{N^ - }\left( {aq} \right) \hfill \\
  {K_a} = 6.2 \times {10^{ - 10}} \hfill \\ 
\end{gathered} $

$(ii)$ $\begin{gathered}
  C{N^ - }\left( {aq} \right) + {H_2}O\left( l \right) \rightleftharpoons HCN\left( {aq} \right) + O{H^ - }\left( {aq} \right) \hfill \\
  {K_b} = 1.6 \times {10^{ - 5}} \hfill \\ 
\end{gathered} $

These equilibria show the following order of the relative base strength

$p{K_a}$ value for acetic acid at the experimental temperature is $5$. The percentage hydrolysis of $0.1\,\,M$ sodium acetate solution will be

The hydrogen ion concentration in weak acid of dissociation constant ${K_a}$ and concentration $c$ is nearly equal to