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 $=30g$
So, moles of benzene $=\frac{30}{78}$
$\because$ Mol. mass of $C_6{H}_6=78$
$=0.385$ Mass of $CC{l}_4=70g$
Moles of $CC{l}_4=\frac{70}{154}$
$(\because$ Mol. mass of $CC{l}_4=15.4)$
$=0.454$
$\therefore$ Mole fraction of benzene
${\chi }_{C_6{H}_6}=\frac{0.385}{0.385+0.454}$ $=0.459$