The mixture which shows positive deviation from Raoult's law is

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Question

The mixture which shows positive deviation from Raoult's law is

Accepted Answer

Correct Answer: D — Ethanol + AcetoneStep-by-step Solution:Positive deviation from Raoult's law occurs when the intermolecular attractive forces between unlike molecules (A–B interactions) are weaker than those in the pure components (A–A and B–B interactions). This causes the vapour pressure of the mixture to be higher than expected.In ethanol + acetone: Pure ethanol has strong H-bonding (O–H···O). When acetone is added, it disrupts the H-bonding network of ethanol (acetone cannot donate H-bonds, only accept them). The A–B interactions are weaker, so the mixture shows positive deviation (vapour pressure higher than ideal).Why other options are incorrect:Benzene + Toluene is nearly ideal (similar structures, similar intermolecular forces) — approximately zero deviation. Acetone + Chloroform shows negative deviation because they form strong H-bonds (Cl₃C–H···O=C) making A–B interactions stronger than pure components. Chloroethane + Bromoethane is nearly ideal — both are polar and structurally similar.Key Concept: Positive deviation — A–B interactions weaker than A–A and B–B. Examples: ethanol+water, acetone+CS₂. Negative deviation — A–B interactions stronger. Examples: acetone+chloroform, HNO₃+water.

The mixture which shows positive deviation from Raoult's law is

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The mixture which shows positive deviation from Raoult's law is

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