According to the NCERT textbook (Section 1.5.2), a solution exhibits positive deviation from Raoult's law when the intermolecular attractive forces between the solute and solvent molecules (A-B) are weaker than those between the solute-solute (A-A) and solvent-solvent (B-B) molecules. This weaker interaction implies that molecules of A (or B) can escape more easily from the solution than from the pure state, resulting in a higher vapour pressure than predicted.

Options stating $\Delta_{mix}H = 0$, $\Delta_{mix}V = 0$, or equal intermolecular forces describe an ideal solution.