Answer:
0.21 atm
Explanation:
Step 1: Given data
Step 2: Calculate the partial pressure of oxygen
The air is a gaseous mixture formed mainly by nitrogen, oxygen and argon. The total pressure is equal to the sum of the partial pressures of the gases.
P = pN₂ + pAr + pO₂
pO₂ = P - pN₂ - pAr
pO₂ = 1 atm - 0.78 atm - 0.01 atm
pO₂ = 0.21 atm