Chemistry - Ionic Equilibrium Question with Solution | TestHub

[S^{2 -}] need for precipitation of

$\text{FeS}=\frac{10^{-18}}{10^{-3}}=10^{-15 }\text{M}$

$\text{MnS}=\frac{10^{-13}}{10^{-3}}=10^{-10 }\text{M}$

$\text{HgS}=\frac{10^{-53}}{10^{-3}}=10^{-5\mathrm{0 }}\text{M}$

$\text{ZnS}=\frac{10^{-24}}{10^{-3}}=10^{-21}\text{M}$

Thus  minimum [S^{2 -}] for precipitation is for HgS it will be precipitated first.