Question

What happens to the temperature in positive deviation?Explain.

Answer 1

In mixtures showing a positive deviation from Raoult's Law, the vapour pressure of the mixture is always higher than you would expect from an ideal mixture.

In positive deviation the vapour pressure is higher than ideal in these mixtures means that molecules are breaking away more easily than they do in the pure liquids.
That is because the intermolecular forces between molecules of A and B are less than they are in the pure liquids.
You can see this when you mix the liquids. Less heat is evolved when the new attractions are set up than was absorbed to break the original ones. Heat will therefore be absorbed when the liquids mix. The enthalpy change of mixing is endothermic. So on increasing temperature the mixer of AB is formed more.