JEE Main201912 Jan 2019Morning ShiftChemistrySolutionsActual
The freezing point of a 4 % aqueous solution of X is equal to the freezing point of a 12 % aqueous solution of Y . If the molecular weight of X is A , then the molecular weight of Y will be
Options
- A2 A
- BA
- C4 A
- D3 A
Correct answer
D. 3 A
Step-by-step solution
Freezing point depression refers to the lowering of the freezing point of solvent upon the addition of solute. ΔT f X = ΔT f Y k f m x = k f m y 4 × 1000 A × 96 = 12 × 1000 M × 88 M = 3 .27 A ≃ 3 A