Question

$Y$ molal solution of a compound in benzene has mole fraction of solute equal to $0.2$. The value of ?

• A. $14$
• B. $3.2$
• C. $1.4$
• D. $2$

Answer 1

The correct option is B $3.2$

Mole fraction of solute in benzene= $0.2$

Mole fracion of benzene= $1-0.2=0.8$

Molecular weight of benzene= $78$; Molality of solution= $x$

$m=\frac{1000\times x_2}{x_1\times M_1}$

$\Rightarrow x=\frac{0.2\times \left(1000\right)}{0.8\times 78}=3.205mol/kg$