Chemistry check you!
1. the partial pressure of oxygen at 310 k in one lung (3.0 l) is 21.3 kpa. how many moles of oxygen are in that lung?
0.025
2. you collect hydrogen gas over water at 323 k. the partial pressure of hydrogen is 122.4, and the total pressure is 134.7 kpa. what is the pressure of the water vapor?
12.3 kpa
3. trimix 10/50 is a gas mixture that contains 10% oxygen and 50% helium, and the rest is nitrogen. if a tank of trimix 10/50 has a total pressure of 2.07 _ 104 kpa, then what is the partial pressure of oxygen?
2.07 * 103 kpa

the ideal gas law equation is as follows

pv = nrt

where p - pressure

v - volume

n - number of moles

r - universal gas constant

t - temperature

so if the pressure, volume and temperature are already known

we are left with n and r

since r is the universal gas constant that has a known fixed value then r too is known

so we are left with 'n'

once we know temperature volume and pressure

we can find the number of moles of gas present using the ideal gas law equation

this is not my own answer, this is an answer for the same question by the user blahblahmali. i do not claim ownership of this account.