• # question_answer If $\alpha$ is the degree of ionization, $C$ the concentration of a weak electrolyte and ${{K}_{a}}$the acid ionization constant, then the correct relationship between $\alpha ,\,\,C$ and ${{K}_{a}}$is [CET Pune 1998; Pb. PMT 1998; RPMT 2002] A)                 ${{\alpha }^{2}}=\sqrt{\frac{{{K}_{a}}}{C}}$       B)                 ${{\alpha }^{2}}=\sqrt{\frac{C}{{{K}_{a}}}}$ C)                 $\alpha =\sqrt{\frac{{{K}_{a}}}{C}}$      D)                 $\alpha =\sqrt{\frac{C}{{{K}_{a}}}}$

According to the Ostwald?s dilution formula ${{\alpha }^{2}}=\frac{K(1-\alpha )}{C}$. But for weak electrolytes a is very small. So that $(1-\alpha )$ can be neglected. So that $\alpha =\sqrt{\frac{{{K}_{a}}}{C}}$.