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$MY$ and $NY_3,$ two nearly insoluble salts, have the same $K_{sp} $ values of $6.2 \times 10^{-13}$ at roomtemperature. Which statement would be true in regard to $MY$ and $NY_3$ ?
The salts $MY$ and $NY_3$ are more soluble in $0.5 \,M\, KY$ than in pure water.
The addition of the salt of $KY$ to solution of $MY$ and $NY_3$ will have no effect on their solubilities.
The molar solubilities of $MY$ and $NY_3$ in water are identical.
The molar solubility of $MY$ in water is less than that of $NY_3$
Solution
For $M Y: K_{s p}=s_{1}^{2}$
$\Rightarrow s_{1}=\sqrt{K_{s p}}=\sqrt{6.2 \times 10^{-13}}$
$=7.87 \times 10^{-7} \mathrm{mol} \mathrm{L}^{-1}$
For $N Y_{3}: K_{s p}=27 s_{2}^{4}$
$\Rightarrow s_{2}=\sqrt[4]{\frac{6.2 \times 10^{-13}}{27}}$
$=3.89 \times 10^{-4} \mathrm{mol} \mathrm{L}^{-1}$
Hence, molar solubility of $MY$ in water is less than that of $NY_3$ .
