Question

If the salts $M_{2}X$ , $Q{Y}_2$ and $P{Z}_3$ have the same solubilities, their $K_{sp}$ values are related as

• A. $K_{sp}(M_{2}K)=K_{sp}(Q{Y}_2)<K_{sp}(P{Z}_3)$
• B. $K_{sp}(M_{2}X)>K_{sp}(Q{Y}_2)=K_{sp}(P{Z}_3)$
• C. $K_{sp}(M_{2}X)=K_{sp}(Q{Y}_2)>K_{sp}(P{Z}_3)$
• D. $K_{sp}(M_{2}X)>K_{sp}(Q{Y}_2)>K_{sp}(P{Z}_3)$

Answer 1

Answer: (A)

For $M_2-X$;
$M_{2}X\rightleftharpoons 2M^{+}+X^{2-}$
$\therefore K_{sp}=(2s{)}^2\times s$
$=4s^2$
For $Q{Y}_2$;
$Q{Y}_2\rightleftharpoons Q^{2+}+2Y^{-}$
$\therefore K_{sp}=s\times (2s{)}^2=4s^2$
For $P{Z}_3$;
$P{Z}_3\rightleftharpoons P^3+3Z^{-}$
$\therefore K_{sp}=s\times (3s{)}^3=27s^4$
Thus, $K_{sp}$ is in order,
$K_{sp}(M_{2}X)=K_{sp}(Q{Y}_2)<K_{sp}(P{Z}_3)$