Question

What is the mole fraction of benzene in solution containing $30\%$ by mass in carbon tetrachloride?

• A. 1.459
• B. 0.459
• C. 4.159
• D. None of these

Answer 1

Answer: (B)

$\because$ Mole fraction of a component
$=\frac{\text { no. of moles of the component }}{\text { total no. of moles of all components }}$
Given, mass of benzene $=30 g$
So, moles of benzene $=\frac{30}{78}$
$\because$ Mol. mass of $C_{6} H_{6}=78$
$=0.385$ Mass of $C C l_{4}=70 g$
Moles of $C C l_{4}=\frac{70}{154}$
$\left(\because\right.$ Mol. mass of $\left.C C l_{4}=15.4\right)$
$=0.454$
$\therefore $ Mole fraction of benzene
$\chi_{C_{6} H_{6}}=\frac{0.385}{0.385+0.454}$ $=0.459$