JEE Main · 2004 · 24 Apr 2004 · Offline · Equilibrium

For a sparingly soluble salt of the type

A B_{4}

(dissociating as

A B_{4} ⇌ A^{4 +} + 4 B^{-}

) whose molar solubility is

s

and whose solubility product is

K_{sp}

, the value of

s

in terms of

K_{sp}

is given by the relation

Answer: (B)

Solution

Read the stoichiometry from the form of the choices, which point to a salt dissolving as

AB X_{4} A X^{4 +} + 4 B X^{-}

. If the molar solubility is

s

, then

[A X^{4 +}] = s

and

[B X^{-}] = 4 s

, so

K_{s p} = s (4 s)^{4} = 256 s^{5}

. Solving for

s

gives

s = (\frac{K _{s p}}{256})^{1/5}

JEE Main · 2004 · 24 Apr 2004 · Offline · Single correct option