Equilibrium Ques 91

91. The solubility product of a sparingly soluble salt $A X_2$ is $3.2 \times 10^{-11}$. Its solubility ( in moles/ litre) is

[2004]

(a) $5.6 \times 10^{-6}$

(b) $3.1 \times 10^{-4}$

(c) $2 \times 10^{-4}$

(d) $4 \times 10^{-4}$

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Answer:

Correct Answer: 91.(c)

Solution:

  1. (c) For $A X_2 ; K _{s p}=4 s^{3}$

$\therefore \quad 3.2 \times 10^{-11}=4 s^{3}$

or $s=3 \sqrt{\frac{3.2 \times 10^{-11}}{4}}=2 \times 10^{-4}$