Consider a binary mixture of volatile liquids. If at ${\mathrm{X}}_{\mathrm{A}}=0.4$ the Vapor pressure of solution is 580 torr than the mixture could be $\left({\mathrm{P}}_{\mathrm{A}}^0=300 \mathrm{torr},{\mathrm{P}}_{\mathrm{B}}^0=800 \mathrm{torr}\right)$

${\mathrm{P}}_{\mathrm{id}\left(\mathrm{AB}\right)}={\mathrm{X}}_{\mathrm{A}}{\mathrm{P}}_{\mathrm{A}}^0+(1-{\mathrm{x}}_{\mathrm{A}}){\mathrm{P}}_{\mathrm{B}}^0$

$={\mathrm{X}}_{\mathrm{A}}({\mathrm{P}}_{\mathrm{A}}^0-{\mathrm{P}}_{\mathrm{B}}^0)+{\mathrm{P}}_{\mathrm{B}}^0$

${\mathrm{P}}_{\mathrm{AB}}^{\mathrm{id}}=0.4 (300 \mathrm{torr}-800 \mathrm{torr}) +800 \mathrm{torr}$

= 600 torr

But given vapor pressure

${\mathrm{P}}_{\mathrm{AB}}=580 \mathrm{torr}$  which is less than what is predicted by Raoult’s law So – ve deviation for

Raoult’s law

∴ Solute –solvent interaction are higher than the solute-solute (or) solvent-solvent interactions (inter molecular for cub between solute solvent are stronger) in option ‘A’ inter molecular hydrogen bond between ${\mathrm{CHCl}}_3$ and acetone which is stronger than dipole-dipole interactions