Chemistry - Ionic Equilibrium Question with Solution | TestHub

What is the minimum$\mathrm{p}\mathrm{H}$required to prevent the precipitation of$\mathrm{Z}\mathrm{n}\mathrm{S}$in a solution that is$0.01\mathrm{}\mathrm{M}$$\mathrm{Z}\mathrm{n}\mathrm{C}{\mathrm{l}}_2$and saturated with$0.10\mathrm{}\mathrm{M}$${\mathrm{H}}_2\mathrm{S}$?
[Given${\mathrm{K}}_{\mathrm{s}\mathrm{p}}=10^{-21},\mathrm{}{\mathrm{K}}_{{\mathrm{a}}_1}\times {\mathrm{K}}_{{\mathrm{a}}_2}=10^{-20}$]