Question

The mole fraction of water in 98% (w/w) $H_{2}S{O}_4$ solution is :

• A. 0.1
• B. 0.9
• C. 0.8
• D. 0.02

Answer 1

The correct option is A 0.1

Mole fraction is defined as the ratio of moles of the one component to the ratio of total number of moles.

so, mole fraction of water = $\frac{\text{moles of water}}{\text{total number of moles}}$

Let mass of $H_{2}S{O}_4$ solution = 100 g
Mass of $H_{2}S{O}_4$=98 g

mass of water $=(100-98)=2g$

So, moles of water = $\frac{2}{18}=0.111moles$

moles of $H_{2}S{O}_4=\frac{98}{98}=1$

so, mole fraction of water = $\frac{0.111}{0.111+1}=0.1$
Option A is correct.