Suppose you have a water solution that is $0\mathrm{.}0010MC{a}^{2+}$ and $0\mathrm{.}0010MM{g}^{2+}.$ You slowly add a concentrated solution of sodium carbonate, $N{a}_{2}C{O}_3,$ to this solution. $K_{sp}$ for

$CaC{O}_3$ is $3\mathrm{.}8{10}^{-9},K_{sp}$ for $MgC{O}_3$ is $1\mathrm{.}0{10}^{-5}.$

a$.$ What would be the concentration of carbonate ion, $C{O}_3^{2-},$ when at least $86\mathrm{.}0\%$ of $C{a}^{2+}$ has been precipitated.

$[C{O}_3^{2-}]=,M$

b$.$ What would be the concentration of carbonate ion, $C{O}_3^{2-},$ when at least $86\mathrm{.}0\%$ of $M{g}^{2+}$ has been precipitated.

$[C{O}_3^{2-}]=,M$