Chemistry - Ionic Equilibrium Question with Solution | TestHub

Second dissociation of${\mathrm{H}}_2\mathrm{S}$is negligible from data
${\mathrm{H}}_2\mathrm{S}\rightleftharpoons {\mathrm{H}}^{+}+\mathrm{H}{\mathrm{S}}^{-}$
$\left[{\mathrm{H}}^{+}\right]=\left[\mathrm{H}{\mathrm{S}}^{-}\right]=\mathrm{x}$
${\mathrm{K}}_1=\frac{\left[{\mathrm{H}}^{+}\right]\left[\mathrm{H}{\mathrm{S}}^{-}\right]}{\left[{\mathrm{H}}_2\mathrm{S}\right]}$
$1\times 10^{-7}=\frac{{\mathrm{x}}^2}{0.1}$
So$\mathrm{x}=10^{-4}$
$\mathrm{p}\mathrm{H}=-\log [{\mathrm{H}}^{+}]$
$=-\log 10^{-4}$
$=4\log 10=4$.