Q. If the various terms in the below given expressions have usual meanings, the van’t Hoff factor (i) cannot be calculated by which one of the expressions?
A) $\pi V = \sqrt{inRT}$
B) $\mathrm{\Delta}T_{f} = ik_{f}.m$
C) $\mathrm{\Delta}T_{b} = ik_{b}.m$
D) $\frac{p{^\circ}_{solvent} - p_{solution}}{p{^\circ}_{solvent}} = i\left( \frac{n}{N + n} \right)$
Explanation
(a)
Van’t Hoff equation is
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \pi V = inRT$
For depression in freezing point,
$\mathrm{\Delta}T_{f} = i \times k_{f} \times m$
For elevation in boiling point,
$\mathrm{\Delta}T_{b} = i \times k_{b} \times m$
For lowering of vapour pressure,
$\frac{p{^\circ}_{solvent} - p_{solution}}{p{^\circ}_{solvent}} = i\left( \frac{n}{N + n} \right)$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.