Chemistry - Ionic Equilibrium Question with Solution | TestHub

$\mathrm{C}\mathrm{a}{\left(\mathrm{O}\mathrm{H}\right)}_2\rightleftharpoons \underset{\left(\mathrm{S}\right)}{\mathrm{C}{\mathrm{a}}^{+2}}+\underset{\left(2\mathrm{S}\right)}{2\mathrm{O}{\mathrm{H}}^{-}}$
$\mathrm{p}\mathrm{H}$of saturated solution$=9$
$\mathrm{p}\mathrm{H}=9,\left[{\mathrm{H}}^{+}\right]={10}^{-9}$
Hence$\left[\mathrm{O}{\mathrm{H}}^{-}\right]=\frac{{10}^{-14}}{{10}^{-9}}={10}^{-5}$
$2\mathrm{s}={10}^{-5},\mathrm{s}=\frac{{10}^{-5}}{2}$
${\mathrm{k}}_{\mathrm{s}\mathrm{p}}$for$\mathrm{C}\mathrm{a}{\left(\mathrm{O}\mathrm{H}\right)}_2\Rightarrow 4{\mathrm{s}}^3$
$\Rightarrow 4\times {\left(\frac{{10}^{-5}}{2}\right)}^3$
$=\frac{{10}^{-15}}{2}=0.5\times {10}^{-15}$