Question

A x molal solution of compound in benzene has a mole fraction of solute equal to 0.2. The value of x is

• A. 14
• B. 3.2
• C. 1.4
• D. 2

Answer 1

Answer: (B)

3.2

Answer 2

The given solution contains that $x$ moles of solute in $1 kg$ of benzene $\therefore$ Moles of benzene $=\frac{1000\,g}{78\,g\,mol^{-1}}=12.8\,mol$ $\therefore 0.2=\frac{x}{x+12.8}; 5=1+\frac{12.8}{x}$ $\frac{12.8}{x}=4 ; x=\frac{12.8}{4}$ $=3.2$