How many kilograms are in a cubic meter of air?

Well this is more of a chemistry question then math questions. It depends on a few factors which you haven't listed. Gas properties under normal conditions can be found using the gas law equation: PV=mRT, where 'P' is the pressure of the gas; V is the volume of the gas; m is the mass of the gas; R is the gas constant; and T is the temp of the gas. So to answer your question, someone would need to know what pressure of the air, the temp of the air. R can be looked up on a chart in most chemistry books or thermodynamics books and V you have given to us. One you have P and T you can solve for m, in kg.