Question

Mole fraction of solute in benzene is 0.2, then find molality of solute.

• A. 3.2
• B. 2.56
• C. 4
• D. 3.6

Answer 1

The correct option is A 3.2

Let the molality of solution = $x$

$\therefore$ Moles of solute in 1000 g benzene

$=\frac{100}{78}=12.82$

Mole fraction of solute

$=\frac{molesofsolute}{Totalmoles}=\frac{x}{x+12.82}$

$0.2=\frac{x}{x+12.82}$

$0.2(x+12.82)=x$

$0.2x+2.564=x$

$2.564=x-0.2x$

$0.8x=2.564$

$x=\frac{2.564}{0.8}=3.2$

Hence, the correct option is $A$