If vapour pressure of pure liquids `'a' % 'B'` are `300` and `800` torr respectively at `25^(@)C`. When these two liquids are mixed at this temperature to form a solution in which mole percentage of `'B'` is `92`, then the total vapour pressure is observed to be `0.95` atm. Which of the following is true for this solution.

Options

A. `DeltaV_("mix")gt0`
B. `DeltaH_("mix")lt0`
C. `DeltaV_("mix")=0`
D. `DeltaH_("mix")=0`

Answer

B

Explanation

According to Raoult's law
`P_(T)=(0.08xx300+0.92xx800)` torr `=(24+736)` torr `=760` torr `=1` atm
`P_("exp.")=0.95 "atm" lt 1` atm
so `DeltaH_("mix")lt0`, and `DeltaV_("mix")lt0`.