A sparingly soluble electrolyte $\mathrm{M_2X}$ ionizes as $\mathrm{M_2X \rightleftharpoons 2M^+ + X^{2-}}$. The solubility product $(K_{sp})$, molal solubility (S) and molal activity coefficient $(\gamma_\pm)$ are related by
(a)$K_{SP} = S^2\gamma_\pm^2$
(b)$K_{SP} = S^3\gamma_\pm^3$
(c)$K_{SP} = 4S^3\gamma_\pm^2$
(d)$K_{SP} = 4S^3\gamma_\pm^3$
Answer
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