Question

Mole fraction of solute in aqueous solution of 30% $NaOH$ is:

• A. 0.16
• B. 0.05
• C. 0.22
• D. 0.95

Answer 1

Answer: (A)

0.16

let us assume, we have 100 g solution.

then, solution of 30% $NaOH$ means $30$ $gm$ $NaOH$ is present in $100$ $g$ solution.

Mass of water $=70$ $gm$

Moles of $NaOH=\frac{30}{40}=0.75$ $moles$

Moles of water $=\frac{70}{18}=3.89$ $moles$

Mole fraction of $NaOH=x_{NaOH}=\frac{0.75}{3.89}=0.22$

Hence, the correct option is $\left(C\right)$