Solid Ba ( NO_3)_2 is gradually dissolved in a 1.0 × 10^-4 M Na_2 CO_3 solution. At which concentration of Ba^2+, precipitate of BaCO_3 begins to…

Solid $\displaystyle \mathrm{Ba}\left(\mathrm{NO}_3\right)_2$ is gradually dissolved in a $\displaystyle 1.0 \times 10^{-4} \mathrm{M} \mathrm{Na}_2 \mathrm{CO}_3$ solution. At which concentration of $\displaystyle \mathrm{Ba}^{2+}$, precipitate of $\displaystyle \mathrm{BaCO}_3$ begins to form ? $\displaystyle \left(\mathrm{K}_{\mathrm{sp}}\right.$ for $\displaystyle \mathrm{BaCO}_3$ $\displaystyle =5.1 \times 10^{-9}$ )