Answer:
4.525% is the percentage by volume of oxygen in the gas mixture.
Explanation:
Total pressure of the mixture = p = 4.42 atm
Partial pressure of the oxygen = [tex]p_1=0.20 atm[/tex]
Partial pressure of the helium = [tex]p_2[/tex]
[tex]p_1=p\times \chi_1[/tex] (Dalton law of partial pressure)
[tex]0.20 atm=4.42 atm\times \chi_1[/tex]
[tex]\chi_1=\frac{0.20 atm}{4.42 atm}=0.04525[/tex]
[tex]\chi_2=1-\chi_1=1-0.04525=0.95475[/tex]
[tex]chi_1+chi_2=1[/tex]
[tex]n_1=0.04525 mol,n_2=0.95475 mol[/tex]
According Avogadro law:
[tex]Moles\propto Volume[/tex] (At temperature and pressure)
Volume occupied by oxygen gas  =[tex]V_1[/tex]
Total moles of gases = n = 1 mol
Total Volume of the gases = V
[tex]\frac{n_1}{V_1}=\frac{n}{V}[/tex]
[tex]\frac{V_1}{V}=\frac{n_1}{n}=\frac{0.04525 mol}{1 mol}[/tex]
Percent by volume of oxygen in the gas mixture:
[tex]\frac{V_1}{V}\times 100=\frac{0.04525 mol}{1 mol}\times 100=4.525\%[/tex]
