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Which of the following statements about solutions and colligative properties is/are correct? (A) A liquid solution of two substances will always freeze entirely at one temperature. (B) A liquid solution of two substances will never freeze entirely at one temperature. (C) On increasing temperature, Henry's constant (K_H) first increases and then decreases for most non-polar gases dissolved in water. (D) For most non-polar gases, the value of K_H is less in benzene than in water.

1. (A)
2. (B)
3. (C)
4. (D)

Correct answer: (B)

Solution

Statement A is false: a two-component solution does not freeze entirely at one temperature; as it cools, one component crystallizes first, changing the concentration, so the freezing point continuously decreases (eutectic behavior). Statement B is true in general for ideal solutions or non-eutectic compositions; only at the eutectic point does a specific mixture freeze at one temperature, but for an arbitrary solution, complete freezing does not occur at one temperature. Statement C is false: for most non-polar gases in water, K_H increases monotonically with temperature up to a point; the behavior described (increase then decrease) is characteristic of gases in non-aqueous solvents, not in water. Statement D is false: non-polar gases are more soluble in non-polar solvents like benzene (like dissolves like), meaning K_H (which is inversely related to solubility) is SMALLER in benzene and LARGER in water. So D has it backwards. The correct answer is B.

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