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A solution of acetone in ethanol :-
A
Shows a negative deviation from Raoult's law
B
Shows a positive deviation from Raoult's law
C
Behaves like a near ideal solution
D
Obeys Raoult's law
Detailed Solution
In pure ethanol the molecules are held together by strong intermolecular hydrogen bonds.
When acetone is added, its molecules get in between the ethanol molecules and break some of these hydrogen bonds.
The new acetone-ethanol interactions are weaker than the ethanol-ethanol interactions they replace.
Because the intermolecular attractions are weakened, the molecules escape more easily into the vapour phase.
The vapour pressure of the solution is therefore higher than that predicted by Raoult's law, with $\Delta H_{mix} \gt 0$ and $\Delta V_{mix} \gt 0$.
So a solution of acetone in ethanol shows a positive deviation from Raoult's law.
When acetone is added, its molecules get in between the ethanol molecules and break some of these hydrogen bonds.
The new acetone-ethanol interactions are weaker than the ethanol-ethanol interactions they replace.
Because the intermolecular attractions are weakened, the molecules escape more easily into the vapour phase.
The vapour pressure of the solution is therefore higher than that predicted by Raoult's law, with $\Delta H_{mix} \gt 0$ and $\Delta V_{mix} \gt 0$.
So a solution of acetone in ethanol shows a positive deviation from Raoult's law.