Chemistry - Ideal Gas Question with Solution | TestHub

At $293\mathrm{\text{K}}, 200\text{mL}$ $\text{He}$ is exhibiting a pressure of $0.66 \text{atm}.$

It occupies $400 \text{mL}$ vessel. Here its partial pressure is reduced to half of its initial pressure.
$\therefore {\text{P}}_{\text{H}\text{e}}$ in the mixture $=0.33$ atm
As $400{\text{mLO}}_2$ at $293\mathrm{\text{K}}$ with a
pressure of $0.52 \text{atm}$ occupies $400 \text{mL}$ volume at $293\mathrm{\text{K}},$ hence its partial pressure its not altered will exhibit $0.52 \text{atm}$.