1. The problem statement, all variables and given/known data 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. 2. Relevant equations Molecular weight of O2=.032kg/L Molecular weight of N2=.028kg/L Molecular weight of CO2 = .044kg/L PV=nRT 3. 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?