Step 1: Write the reaction and assume initial concentration of \(A_2B_3\) is \(C\), and degree of dissociation is \(\alpha\).
\[ A_2B_3(aq)\rightleftharpoons 2A^{3+}(aq)+3B^{2-}(aq) \]
At equilibrium:
\[ [A_2B_3]=C(1-\alpha) \] \[ [A^{3+}]=2C\alpha \] \[ [B^{2-}]=3C\alpha \]
Step 2: Write the expression for equilibrium constant \(K_{eq}\).
\[ K_{eq}=\frac{[A^{3+}]^2[B^{2-}]^3}{[A_2B_3]} \]
Substituting the equilibrium concentrations:
\[ K_{eq}=\frac{(2C\alpha)^2(3C\alpha)^3}{C(1-\alpha)} \]
Step 3: Simplify the expression.
\[ K_{eq}=\frac{4C^2\alpha^2 \cdot 27C^3\alpha^3}{C(1-\alpha)} \] \[ K_{eq}=\frac{108C^5\alpha^5}{C(1-\alpha)} \] \[ K_{eq}=\frac{108C^4\alpha^5}{1-\alpha} \]
Step 4: For a weak electrolyte, \(\alpha\) is very small, so \(1-\alpha \approx 1\).
Therefore, \[ K_{eq}=108C^4\alpha^5 \] \[ \alpha^5=\frac{K_{eq}}{108C^4} \] \[ \alpha=\left(\frac{K_{eq}}{108C^4}\right)^{1/5} \]
Final Answer:
\[ \boxed{\alpha=\left(\frac{K_{eq}}{108C^4}\right)^{1/5}} \]
So, the correct option is (B)
What will be the equilibrium constant of the given reaction carried out in a \(5 \,L\) vessel and having equilibrium amounts of \(A_2\) and \(A\) as \(0.5\) mole and \(2 \times 10^{-6}\) mole respectively?
The reaction : \(A_2 \rightleftharpoons 2A\)

Cobalt chloride when dissolved in water forms pink colored complex $X$ which has octahedral geometry. This solution on treating with cone $HCl$ forms deep blue complex, $\underline{Y}$ which has a $\underline{Z}$ geometry $X, Y$ and $Z$, respectively, are
At \(-20^\circ \text{C}\) and 1 atm pressure, a cylinder is filled with an equal number of \(H_2\), \(I_2\), and \(HI\) molecules for the reaction:
\[H_2(g) + I_2(g) \rightleftharpoons 2HI(g)\] The \(K_P\) for the process is \(x \times 10^{-1}\).
(x = ___________)
Given: \(R = 0.082 \, \text{L atm K}^{-1} \text{mol}^{-1}\)
What will be the equilibrium constant of the given reaction carried out in a \(5 \,L\) vessel and having equilibrium amounts of \(A_2\) and \(A\) as \(0.5\) mole and \(2 \times 10^{-6}\) mole respectively?
The reaction : \(A_2 \rightleftharpoons 2A\)