Answer:
6.79 atm
Explanation:
Applying Dalton's law of partial pressure:
[tex]P_{total} = P_{helium} + P_{oxygen}[/tex], where [tex]P_{total}[/tex] = total partial pressure of all the component gases in the mixture, [tex]P_{helium}[/tex] = partial pressure of helium gas, and [tex]P_{oxygen}[/tex] = partial pressure of oxygen gas.
From the illustration, [tex]P_{total}[/tex] = 7.00 atm and [tex]P_{oxygen}[/tex] = 0.21 atm. Hence, the partial pressure due to helium is calculated such that:
[tex]P_{helium}[/tex] = [tex]P_{total} - P_{oxygen}[/tex]
= 7.00 - 0.21
= 6.79 atm
Therefore, the partial pressure due to helium in order to maintain the pressure due to oxygen at 0.21 atm would be 6.79 atm.