The mixture which shows positive deviation from Raoult’s law is: 

Mixture of ethanol and acetone shows positive deviation from Raoult’s Law. In pure ethanol, molecules are hydrogen bonded. Between acetone molecules, force of attraction are dipole-dipole attraction. When both are added, hydrogen bond between ethanol and dipole-dipole attractions between acetone molecules are cleaved strong force of attractions are cleaved and weak force of attraction are formed between alcohol and acetone.
Each liquid from mixture vapourises readily.
(1) Benzene + toulene is an ideal solution.
(2) Acetone + chloroform shows negative deviation.
(4) Chloroethane + bromoethane is an ideal solution.