Answer: Acetone and chloroform.
- A Benzene and toluene
- B Ethanol and water
- C n-hexane and n-heptane
- D Acetone and chloroform
Correct answer: D. Acetone and chloroform
Explanation: Acetone and chloroform form intermolecular hydrogen bonds, so A-B attractions exceed A-A and B-B, giving negative deviation.
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.