alleryFor a solution of a non-volatile solute, Raoult law implies that the vapour pressure of the pure solvent
ARises as solute is added
BFalls linearly with solute mole fraction
CIs unchanged
DFalls exponentially with solute mole fraction
Answer & Solution
Correct answer: B. Falls linearly with solute mole fraction
1. Raoult law: p_A = x_A × p_A° for volatile solvent A.
2. If a non-volatile solute is added, the solvent mole fraction x_A drops below 1.
3. Therefore the vapour pressure of the solvent falls linearly as x_solute increases.
4. This lowering is the basis for colligative properties like boiling point elevation.
_Source: syllabus Chemistry, Unit 1 "Solutions", §1.5_
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