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🧪 Chemistry  ·  Solutions  ·  NEET & JEE

Compared with the pure solvent, the boiling point of a solution containing a non-volatile solute is:

Answer: higher.

  • A lower
  • B higher
  • C the same
  • D unrelated

Correct answer: B. higher

Explanation: Dissolving a non-volatile solute lowers the vapour pressure, so a higher temperature is needed to boil the solution.

Vapour Pressure: Pure Solvent vs SolutionTVapour PPure solventSolution (lower VP)ΔTfTf(soln)Tf(pure)Dissolved solute lowers vapour pressure at every temperature, shifting Tf down and Tb up

Adding a non-volatile solute lowers the solvent's vapour pressure at every temperature, which is the root cause behind all four colligative properties: it shifts the freezing point down and the boiling point up.

Concept context

Learn how substances dissolve and form mixtures. Covers concentration terms, colligative properties (boiling point elevation, freezing point depression, osmotic pressure), and ideal vs non-ideal solution behaviour.

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