Answer: Nature of solvent only.
- A Nature of solute only
- B Nature of solvent only
- C Both solute and solvent
- D Temperature of solution
Correct answer: B. Nature of solvent only
Explanation: Kf is a property of the solvent only. For water Kf = 1.86 K kg/mol; benzene Kf = 5.12 K kg/mol.
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.