Question

Equimolar solutions in the same solvent have :

• A. different boiling and different freezing points
• B. same boiling and same freezing points
• C. same freezing point but different boiling point
• D. same boiling point but different freezing point

Answer 1

Answer: (B)

same boiling and same freezing points

Answer 2

Boiling point and freezing point depend on $K_b$ (molal elevation constant) and $K_f$ (molal depression constant) of the solvent. Thus equimolar solution (of the non-electrolyte) will have same boiling point and also same freezing point. $\Delta T_{f} = K_{f} \times$ molality $\Delta T_{b} = K_{b} \times$ molality In question (139) set C, nature of solute has not been mentioned. Hence, we have assumed that solute is non-electrolyte.