Which property is a classic example of a colligative property?

• A. Raoult's Law
• B. Henry's Law
• C. Mass percent
• D. Boiling Point Elevation

Answer: (D)

Colligative properties depend on the number of dissolved particles, not what those particles are. When a nonvolatile solute is added to a solvent, the solvent’s vapor pressure drops, so the solution must be heated to a higher temperature to reach the same vapor pressure as the pure solvent—this is boiling point elevation. The shift in boiling point is related to how many particles are present (ΔTb ≈ i Kb m for dilute solutions), showing the direct link to particle count. Among the options, boiling point elevation clearly embodies a colligative property, unlike Raoult’s Law (vapor pressure behavior of ideal solutions), Henry’s Law (gas solubility in liquids), or mass percent (a concentration measure).