[ $\mathrm{AB}_2$ નું મોલર દળ $=200 \mathrm{~g} \mathrm{~mol}{ }^{-1}$, પાણીનું ઉત્કલનબિંદુ $=100^{\circ} \mathrm{C}, \mathrm{K}_{\mathrm{b}}$ (પાણીનો મોલલ ઉત્કલનબિંદુ ઉન્નયન અચળાંક $\left.=0.52 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}\right)$ ]
$\mathrm{i}=1+(3-1) \alpha$
$\mathrm{i}=1+2 \alpha$
$\Delta \mathrm{T}_{\mathrm{b}}=\mathrm{k}_{\mathrm{b}} \mathrm{im}$
$0.52=0.52(1+2 \alpha) \frac{\frac{10}{200}}{\frac{100}{1000}}$
$1=(1+2 \alpha) \frac{10}{20}$
$2=1+2 \alpha$
$\alpha=0.5$
Ans. $\alpha=5 \times 10^{-1}$