Question

If the various terms in the given below expressions have usual meanings, the van't Hoff factor $(i)$ cannot be calculated by which one of the following expressions

• A. $\pi V=\sqrt{i n R T}$
• B. $\Delta T_f=i K_f \cdot m$
• C. $\Delta T_b=i K_b \cdot m$
• D. $\frac{P_{\text {solvent }}^{\circ}-P_{\text {solution }}}{P_{\text {solvent }}^{\circ}}=i\left(\frac{n}{N+n}\right)$

Answer 1

Answer: (A)

Van't Hoff equation is $\pi V=i n R T$
For depression in freezing point.
$\Delta T_f=i \times K_f \times m$
For elevation in boiling point.
$\Delta T_b=i \times K_b \times m$
For lowering of vapour pressure,
$\frac{P_{\text {solvent }}^{\circ}-P_{\text {solution }}}{P_{\text {solvent }}^{\circ}}=i\left(\frac{n}{N+n}\right)$