Question

The substance A, when dissolved in solvent B, shows the molecular mass corresponding to $A_3$. The Vant Hoff's factor will be:

• A. $1$
• B. $2$
• C. $3$
• D. $1/3$

Answer 1

Answer: (D)

$1/3$

Let us consider the formula of vant hoff factor ,

$i=\frac{normalmolecularweight}{observedmolecularweight}$

Let $A$ be $xgmo{l}^{-1}$ of normal molecular weight

Therefore, Observed molecular weight becomes $3xgmo{l}^{-1}$ as molecule of $A$ becomes $A_3$

Hence,

$i=\frac{x}{3x}=\frac{1}{3}$