JEE Main · 2024 · 31 Jan 2024 · Shift 1 · Solutions

Identify the mixture that shows positive deviations from Raoult's Law

(A) $(CH_{3})_{2} CO + C_{6} H_{5} NH_{2}$
(B) $CHCl_{3} + C_{6} H_{6}$
(C) $CHCl_{3} + (CH_{3})_{2} CO$
(D) $(CH_{3})_{2} CO + CS_{2}$ ✓ Correct

Answer: (D)

Solution

Positive deviation from Raoult's law occurs when solute-solvent interactions are weaker than the solute-solute and solvent-solvent interactions in the pure components, so escaping tendency (vapour pressure) increases on mixing.

Acetone and

C S_{2}

are dissimilar in nature (acetone is polar with a hydrogen-bond-accepting C=O;

C S_{2}

is non-polar), so the mixture shows positive deviation from Raoult's law. The other pairs listed (acetone-aniline, chloroform-benzene, chloroform-acetone) are examples of negative deviation, due to hydrogen bonding or dipole-dipole interactions between unlike molecules.

JEE Main · 2024 · 31 Jan 2024 · Shift 1 · Single correct option

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JEE Main · 2024 · 31 Jan 2024 · Shift 1 · Solutions

Solution

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