Answer: mole fraction.
- A its total mass
- B mole fraction
- C its molar volume
- D its mass density
Correct answer: B. mole fraction
Explanation: For an ideal solution, p_A = p°_A·x_A, where x_A is the mole fraction of A.
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.