Chemistry - Ionic Equilibrium Question with Solution | TestHub

What is the minimum$\text{pH}$needed to prevent the precipitation of$\text{ZnS}$in a solution i.e.$\text{0}\text{.01}\text{M}{\text{ZnCl}}_{\text{2}}$and saturated with$\text{0}\text{.1}\text{M}{\text{H}}_{\text{2}}\text{S}$?
Given:
${\text{K}}_{\text{sp}}$of$\text{ZnS}\text{=}{\text{10}}^{-\text{21}}$
$\text{Ka}$of${\text{H}}_{\text{2}}\text{S}\text{=}{\text{10}}^{-\text{20}}$