A mixture of 100 m mol of Ca ( OH )_2 and 2 g of sodium sulphate was dissolved in water and the volume was made up to 100 mL. The mass of calcium…

A mixture of $\displaystyle 100$ m mol of $\displaystyle \mathrm{Ca}(\mathrm{OH})_2$ and $\displaystyle 2$ g of sodium sulphate was dissolved in water and the volume was made up to $\displaystyle 100$ mL . The mass of calcium sulphate formed and the concentration of $\displaystyle \mathrm{OH}^{-}$in resulting solution, respectively, are : (Molar mass of $\displaystyle \mathrm{Ca}(\mathrm{OH})_2, \mathrm{Na}_2 \mathrm{SO}_4$ and $\displaystyle \mathrm{CaSO}_4$ are $\displaystyle 74$, $\displaystyle 143$ and $\displaystyle 136 \mathrm{~g} \mathrm{~mol}^{-1}$, respectively ; $\displaystyle \mathrm{K}_{\mathrm{sp}}$ of $\displaystyle \mathrm{Ca}(\mathrm{OH})_2$ is $\displaystyle 5.5 \times 10^{-6}$ )