Consider a binary solution having components A and B.

If the force of attraction between molecules of and A and B in the solution are weaker than that of between  A — A and B — B, then the chances of beraking of the molecules of A—B from the solution is high to exist as A-A and B-B. The total pressure of the solution will be greater than the corresponding vapour pressure of ideal solution of the same component  A and B.

This type of solution will show a positive deviation from Raoults law.