Chemistry - Ionic Equilibrium Question with Solution | TestHub

$$\begin{array}{rl}& {\mathrm{CaSO}}_{4(s)}\rightleftharpoons {\mathrm{Ca}}^{2+}{}_{(aq)}+{\mathrm{SO}}_4{}^{2-}{}_{(aq)}\\ & S\\ & K_{sp}=S^2=9\times 10^{-6}\\ & S=3\times 10^{-3}\mathrm{mol}{\mathrm{L}}^{-1}\end{array}$$ Solubility in $\mathrm{g}$ litre ${}^{-1}=$ molecular mass $\times S$ $$=136\times 3\times 10^{-3}=408\times 10^{-3}\mathrm{g}{\mathrm{L}}^{-1}$$ $408\times 10^{-3}\mathrm{g}$ of ${\mathrm{CaSO}}_4$ present in 1 litre $1\mathrm{g}$ of ${\mathrm{CaSO}}_4$ present is $\frac{1}{408\times 10^{-3}}=2.45$ litre