# Solve the following

Question:

At $35^{\circ} \mathrm{C}$, the vapour pressure of $\mathrm{CS}_{2}$ is $512 \mathrm{~mm} \mathrm{Hg}$ and that of acetone is $344 \mathrm{~mm} \mathrm{Hg}$. A solution of $\mathrm{CS}_{2}$ in acetone has a total vapour pressure of $600 \mathrm{~mm} \mathrm{Hg}$. The false statement amongst the following is:

1. Raoult's law is not obeyed by this system

2. a mixture of $100 \mathrm{~mL} \mathrm{CS}_{2}$ and $100 \mathrm{~mL}$ acetone has a volume $<200 \mathrm{~mL}$

3. $\mathrm{CS}_{2}$ and acetone are less attracted to each other than to themselves

4. heat must be absorbed in order to produce the solution at $35^{\circ} \mathrm{C}$

Correct Option: , 2

Solution:

Mixture of carbon disulphide and acetone will show positive deviation from Raoult's Law.

The dipolar interaction between solute $\left(C S_{2}\right)$ solvent (acetone) molecules in solution are weaker. So the vapour pressure of solution will be greater than the individual vapoure pressure of pure components.