MHTCET 23 Apr 2025 Shift 2 Paper

Concept:Raoult's law is obeyed only by ideal solutions, in which the intermolecular forces between unlike molecules ($\mathrm{A{-}B}$) are nearly equal to those between like molecules ($\mathrm{A{-}A}$ and $\mathrm{B{-}B}$).Explanation:When $\mathrm{A{-}B}$ interactions differ greatly from $\mathrm{A{-}A}$ and $\mathrm{B{-}B}$ interactions, the mixture shows positive or negative deviation from Raoult's law.Phenol and aniline: both form strong intermolecular hydrogen bonds, so they show negative deviation and are non-ideal.Chloroform and acetone: strong hydrogen-bond-like interactions occur between chloroform and acetone, leading to large negative deviation; hence non-ideal.Ethanol and acetone: ethanol acts as a hydrogen-bond donor and acetone as an acceptor, which changes the escaping tendency of molecules and causes deviation from Raoult's law.Benzene and toluene: both are non-polar hydrocarbons with similar molecular sizes and weak van der Waals forces, so their mixtures behave nearly ideally and obey Raoult's law.Answer:Option D – Benzene and toluene