d
\(K_{a}\left(N H_{4} O H\right)=1.77 \times 10^{-5}\)

\({N H_{4} O H \rightleftharpoons N H_{4}^{+}+O H^{-}}\)

\({K_{a}=\frac{\left[N H_{4}^{+}\right]\left[O H^{-}\right]}{\left[N H_{4} O H\right]}}\)\({=1.77 \times 10^{-5} \ldots .(i)}\)

Hydrolysis of \(N H_{4} C l\) takes place as,

\(N H_{4} C l+H_{2} O \rightarrow N H_{4} O H+H C l\)

\(\quad N H_{4}^{+}+H_{2} O \rightarrow N H_{4} O H+H^{+}\)

Hydrolysis constant, \(K_{h}=\frac{\left[N H_{0} O H\right]\left[H^{+}\right]}{\left[N H_{4}^{+}\right]} \ldots \ldots(i i)\)

\( \quad K_{h}=\frac{\left[N H_{4} O H\right]\left[H^{+}\right]\left[O H^{-}\right]}{\left[N H_{4}^{+}\right][O H]} \ldots \ldots(i i i)\)

From Eqs. \((i)\) and \((iii)\)

\({K_{h}=\frac{K_{w}}{K_{a}}}\) \({\left[\therefore\left[H^{+}\right]\left[O H^{-}\right]=K_{w}\right]}\)

\({=\frac{10^{-14}}{1.77 \times 10^{-5}}=5.65 \times 10^{-10}}\)