Answer :
Answer: The partial pressure of oxygen in the tank is 82.95 kPa.
Explanation:
According to Raoult's law, the partial pressure of a component at a given temperature is equal to the mole fraction of that component multiplied by the total pressure.
[tex]p_{O_2}=x_{O_2}\times P[/tex]
where,
[tex]p_{O_2}[/tex] = partial pressure of oxygen
[tex]x_{O_2}[/tex] = mole fraction of oxygen
[tex]P[/tex] = Total pressure
[tex]x_{O_2}=\frac{n_{O_2}}{n_{O_2}+n_{He}}[/tex],
where [tex]n_{O_2}[/tex] = moles of oxygen =[tex]\frac{68g}{32g/mol}=2.125[/tex]
[tex]n_{He}[/tex] = moles of Helium =[tex]\frac{32g}{4g/mol}=8[/tex]
[tex]x_{O_2}=\frac{2.125}{2.125+8}=0.210[/tex]
[tex]p_{O_2}=0.210\times 395kPa=82.95kPa[/tex]
Thus the partial pressure of oxygen in the tank is 82.95 kPa.