A compound ${\mathrm{MX}}_2$ has observed and normal molar masses 65.6 and 164 respectively. Calculate the apparent degree of ionization of ${\mathrm{MX}}_2$:

$\begin{array}{l}\mathrm{i}=\frac{\mathrm{Normal} \mathrm{molar} \mathrm{mass}}{\mathrm{Observed} \mathrm{molar} \mathrm{mass}}\\ =\frac{164}{65.6}=2.5\\ \mathrm{\alpha }=\frac{\mathrm{i}-1}{\mathrm{n}-1},\mathrm{n}=3(\mathrm{number} \mathrm{of} \mathrm{ions})\\ =\frac{2.5-1}{3-1}=\frac{1.5}{2}=0.75\end{array}$

$\therefore$ Percentage ionization of ${\mathrm{MX}}_2$ will be 75%.