Chemistry - Liquid Solution Question with Solution | TestHub

For AB
$\begin{array}{rl}& \Delta {\mathrm{T}}_{\mathrm{b}}=2.7\mathrm{K}\\ & 2.7=1\times 0.5\times \mathrm{m}\\ & \mathrm{m}=\frac{27}{5}\end{array}$
Let molar mass of $\mathrm{AB}=\mathrm{x}$.
$\begin{array}{rl}& \text{ So }\frac{1/x}{15}\times 1000=\frac{27}{5}\\ & x=12.34\end{array}$
For ${\mathrm{AB}}_2$
$\begin{array}{rl}& \Delta {\mathrm{T}}_{\mathrm{b}}=1.5\mathrm{K}\\ & 1.5=1\times 0.5\times \mathrm{m}\\ & \mathrm{m}=3\end{array}$
Let molar mass of ${\mathrm{AB}}_2=\mathrm{y}$
So $\frac{1/\mathrm{y}}{15}\times 1000=3$
$\begin{array}{rl}& y=\frac{1000}{45}\\ & y=22.22\end{array}$
Now let a and b be atomic masses of A and B respectively, then
$\begin{array}{rl}& \mathrm{A}+\mathrm{b}=12.34...(i)\\ & \mathrm{A}+2\mathrm{b}=22.22...(ii)\\ & \mathrm{B}=22.22-12.34=9.88\\ & \text{ Now }\mathrm{a}=12.34-9.88=2.46\\ & =24.6\times 10^{-1}=25\times 10^{-1}\end{array}$