Hi

As you asked that the question according to the question.

A mixture of methanol and acetone shows positive deviation from Raoult's Law. Pure methanol

possesses hydrogen bonding. Introduction of acetone between the molecules of methanol results in

breaking of some of these hydrogen bonds. Due to weakening of interactions, the answer shows positive

deviation from Raoult's law.

Hope helpful.

Methanol and Acetone

It is because, the interaction between acetone and methanol is weaker than the interaction between acetone -acetone and methanol-methanol. In pure methanol molecules are hydrogen bonded.As acetone is added in methanol some of the H-bonding interaction break between methanol and molecules as acetone molecules are added between them. Due to weakening of interaction the vapour pressure of mixture of acetone and methanol is higher than the molecules in pure state.

I hope it helps you, as your question was incomplete I gave an answer which is generally asked with the question you mentioned one from the question bank of JEE mains.