Question

A mixture of $He$ and $S{O}_2$ at one bar pressure contains $20\%$ by weight of $He$. Partial pressure of $He$ be:

• A. 0.2 bar
• B. 0.4 bar
• C. 0.6 bar
• D. 0.8 bar

Answer 1

The correct option is D 0.8 bar

Mixture contains 20g $He$ and 80g $S{O}_4$

No of moles of $He$ = 20/4 = 5 mol

No of moles of $S{O}_4$ = 80/64 = 1.25 mol

Mole Fraction of $He$ = 5/6.25 = 0.8

And Partial Pressure of $He$= 0.8 x 1 bar

= 0.8 bar