Assertion: If on mixing the two liquids, the solution becomes hot, it implies that it shows negative deviation from Raoults law.

Reason: Solution which show negative deviation are accompanied by a decrease in volume.

Explanation:

Raoult's law states that the partial pressure of each component in a mixture of ideal liquids is proportional to its mole fraction. However, in real solutions, the behavior of the components may deviate from the ideal behavior.

Negative deviation from Raoult's law occurs when the attractive forces between the molecules of the components in the mixture are stronger than the attractive forces between the molecules of the same component in its pure state. As a result, the vapor pressure of the mixture is less than what is predicted by Raoult's law.

When two liquids that show negative deviation from Raoult's law are mixed, heat is evolved. This is because the energy required to break the stronger intermolecular forces between the molecules of the two components is greater than the energy released when the new, weaker intermolecular forces are formed in the solution. Thus, the negative deviation is accompanied by an exothermic heat of mixing.

Furthermore, negative deviation from Raoult's law is accompanied by a decrease in volume. This is because the molecules of the two components pack together more closely in the solution than they do in their pure states. The decrease in volume is also responsible for the evolution of heat when the two liquids are mixed.

Therefore, the assertion that if on mixing the two liquids, the solution becomes hot, it implies that it shows negative deviation from Raoult's law, is true. The reason that solution which show negative deviation are accompanied by a decrease in volume is also true.