Question

Which of the following sulphides is more soluble in pure water?

• A. $CdS$
• B. $NiS$
• C. $SnS$
• D. Equal solubility for all

Answer 1

The correct option is A $CdS$

Among $CdS,NiS$ and $SnS$, the sulphide with lowest value of $K_{sp}$ is $CdS$. Hence, more soluble in pure water
Note: For $CdS$, solubility $S=\sqrt{K_{sp}}=\sqrt{1.5\times {10}^{-28}}=1.2\times {10}^{-14}M$