Identify the mixture that shows positive deviations from Raoult's law

Options

A. `CHCl_(3)+(CH_(3))_(2)CO`
B. `(CH_(3))_(2)CO+C_(6)H_(5)NH_(2)`
C. `CHCl_(3)+C_(6)H_(6)`
D. `(CH_(3))_(2)CO+CS_(2)`

Answer

D

Explanation

Acetone is a polar solvent where as `CS_(2)` is a non–polar solvent. The cohesive forces are stronger than adhesive forces in the solution so it will increase the vapour pressure as against the prediction by Raoult’s law. So it will show a positive deviation. Due to formation of hydrogen bonds between different molecules of different components in option (a), (b), (c) and (e) these compound will show negative deviation from Raoult’s law.
Due to positive charged H–atom of `CHCl_(3)` and negative charged `pi` –electrons of benzene ring the intermolecular forces between molecules of chloroform and benzene increases. So the vapour pressure of solution decreases against the prediction by Raoult’s law.