Help with mass and molar concentrations

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To determine the mass and molar concentrations of O2, CO2, and N2 in air at 37 °C and 1.0 atm, assume a volume of 1 L for calculations. The percentages provided represent mole fractions, not mass percentages, allowing the use of the ideal gas law. Using the molecular weights of the gases, the mass concentrations can be calculated based on their respective mole fractions. The ideal gas law can be simplified by deriving a formula that cancels out volume, focusing on the relationship between moles and concentration. This approach clarifies the confusion regarding the initial parameters and leads to the desired concentrations.
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Homework Statement


At 37 ° C and 1.0 atm of pressure, air is 21.2% O2, 0.15 % CO2 and 78.65 % N2. Determine the mass and molar concentrations of each of the gases in the air.


Homework Equations


Molecular weight of O2=.032kg/L
Molecular weight of N2=.028kg/L
Molecular weight of CO2 = .044kg/L
PV=nRT

The Attempt at a Solution


I don't know how to start because I am not given V, mass, or number of moles (so the ideal gas law isn't useful). I am also not sure if the percentages given are in terms of mass/volume/number of moles so I am very confused. How should I approach this problem?
 
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Assume V = 1L. Alternatively derive formula for concentration using V as a variable - in the end it will miraculously cancel out. These are not mass percentages (think what Avogadro's law tells you about volume/moles).
 
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