Question

A closed vessel contains helium and ozone at a pressure of P atm. The ratio of He and oxygen atoms is 1:1. If helium is removed from the vessel, the pressure of the sytem will reduced to :

• A. 0.5 P atm
• B. 0.75 P atm
• C. 0.25 P atm
• D. 0.33 P atm

Answer 1

The correct option is A 0.5 P atm

$He$ and $O_3$ has equal number of molecules

So, mole fraction is also equal of each component

Partial pressure= $\frac{1}{2}$ of total pressure

So, when we remove the $He$ the partial pressure of $He$ is removed.

So, $P$ goes to $P/2\Rightarrow 0.5Patm$