Intermolecular forces between two benzene molecules are nearly of same strength as those between two toluene molecules. For a mixture of benzene and toluene, which of the following are not true?

A solution of benzene and toluene constitutes an ideal solution. An ideal solution is one that follows Raoult’s Law over the entire range of all concentrations. Raoult’s law states that, “for a solution of volatile liquids the partial vapour pressure of each component of the solution is directly proportional to its mole fraction present in solution.” Ideal solutions have two major properties that the (1) enthalpy of mixing of the pure components to form the solution is zero and (2) the volume of mixing is also zero. Hence ΔmixH = zero and ΔmixV = zero. Hence, option (i) and (ii) are true. Also, since the solution formed is ideal in nature, it does not show positive and negative deviation from Raoult’s law, hence it does not form an azeotrope. Hence, (iii) and (iv) are not true about the solution.

The correct options are (iii) and (iv).