$\mathrm{M}(\mathrm{OH}{)}_{\mathrm{x}}\text{ has }{\mathrm{K}}_{\mathrm{sp}}=4\times {10}^{-12}\text{ and solubility }1\times {10}^{-4}\mathrm{M}\text{. What is the value of }\mathrm{X}\text{ ? }$

$\begin{array}{l}\mathrm{M}(\mathrm{OH}{)}_{\mathrm{x}}\rightleftharpoons {\mathrm{M}}^{\mathrm{x}+}+\mathrm{x}{\mathrm{OH}}^{-}\\ {\mathrm{K}}_{\mathrm{sp}}={\mathrm{x}}^{\mathrm{x}}(\mathrm{s}{)}^{\mathrm{x}+1}\\ 4\times {10}^{-12}={\mathrm{x}}^{\mathrm{x}}{\left(1\times {10}^{-4}\right)}^{\mathrm{x}+1}\end{array}$

$\begin{array}{l}\text{ If }\mathrm{x}=1,4\times {10}^{-12}={\left(1\times {10}^{-4}\right)}^2=1\times {10}^{-8}\text{ (Incorrect) }\\ \text{ If }\mathrm{x}=2,4\times {10}^{-12}=2^2{\left(1\times {10}^{-4}\right)}^{2+1}=4\times {10}^{12}\text{ (Correct) }\end{array}$