Answer: zero.
- A zero
- B positive
- C negative
- D very large
Correct answer: A. zero
Explanation: An ideal solution obeys Raoult law over all compositions, and for it both delta<sub>mix</sub>H and delta<sub>mix</sub>V are zero.
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.