The values of Ksp of CaCO_3 and CaC_2 O_4 are 4.7 × 10^-9 and 1.3 × 10^-9 respectively at 25°C. If the mixture of these two is washed with water,…

The values of Ksp of $\displaystyle \mathrm{CaCO}_3$ and $\displaystyle \mathrm{CaC}_2 \mathrm{O}_4$ are $\displaystyle 4.7 \times 10^{-9}$ and $\displaystyle 1.3 \times 10^{-9}$ respectively at $\displaystyle 25$°C. If the mixture of these two is washed with water, what is the concentration of $\displaystyle \mathrm{Ca}^{2+}$ ions in water ?