Question

Equimolar solutions in the same solvent have
A. Different boiling and different freezing points
B. same boiling and same freezing point
C. same freezing point but different boiling point
D. same boiling point but different freezing point.

Answer 1

Equimolar solutions are the solution which contains the same number of moles of solute dissolved in a solvent. Hence the concentration of the solution or molarity or molality will be the same. The colligative properties are the physical changes in the solution which results from the addition of solute to the solvent.

Complete step by step answer:
Boiling point of the solution is the point at which the solution starts to boil. The boiling point of the solution changes with the number of moles of solute added to the solution.
The freezing point of the solution is the point at which the solution starts to freeze. The freezing point of the solution changes with the number of moles of solute added to the solution.
Both the depression in freezing point of the solution and elevation of boiling point of solution are the colligative properties as their value changes with the amount of solute added to the solution.
If equimolar solute is present in the equimolar solution in the same solvent then the solution will have the same value for boiling point and freezing point.
Therefore, the correct option is B.

Note:
The colligative properties like boiling point and freezing point do not depend on the type of solute which is added but they do depend on the type of solvent used. The boiling point of the solvent present above the solution will always be greater than the boiling point of the pure solvent. It does not matter whether the solute present in the solution is volatile solute or non-volatile solute.