Question

A liquid possessing which of the following characteristics will be most suitable for determining the molecular mass of a compound by cryoscopic measurements?

• A. That having low freezing point and small enthalpy of fusion
• B. That having high freezing point and small enthalpy of fusion
• C. That having low freezing point and small enthalpy of vapourization.
• D. That having large surface tension

Answer 1

The correct option is B That having high freezing point and small enthalpy of fusion

Try to recall the formula what we just discussed.
The relation between molal depression constant and enthalpy of fusion.
$K_f=\frac{M{w}_A\times R\times T_f^2}{{\Delta }_{fus}H\times 1000}$
Now $K_f\propto \frac{T_f^2}{{\Delta }_{fus}H}$
$K_f$ should be high so as to get a high value of $\Delta T_f$.