Calculate the minimum mass of ${\mathrm{AB}}_2$ (s) which must be added to 100 mL water (in mg) to form a saturated solution.

$\begin{array}{l}{\mathrm{K}}_{\mathrm{sp}}\left({\mathrm{AB}}_2\right)=3.2\times {10}^{-11}\\ {\mathrm{M}}_{\mathrm{w}.\mathrm{t}}\left[{\mathrm{AB}}_2\left(\mathrm{s}\right)\right]=100\mathrm{g}/\mathrm{mole}\end{array}$