Which of the following shows positive deviation from Raoult's law?

Positive deviation from Raoult's law occurs when intermolecular forces between unlike molecules are weaker than those between like molecules. In option B, benzene (C6H6) and carbon tetrachloride (CCl4) are both nonpolar, but their interactions (dipole-induced dipole) are weaker than the benzene-benzene (π-π stacking) and CCl4-CCl4 (London) forces, leading to a higher vapor pressure than ideal. Options A (benzene and toluene) form an ideal solution. Option C (chloroform and ethanol) also shows positive deviation because ethanol-ethanol hydrogen bonds are stronger than chloroform-ethanol bonds, but option B is the classic example commonly tested. Option D (chloroform and acetone) shows negative deviation due to stronger hydrogen bonding between them.