Estimate the mass of air in your class room at NTP. Here NTP implies normal temperature (room temperature) and 1 atmospheric pressure.

Explanation

The average size of a class is 6 m length, 5 m breadth and 4 m height. The volume of the room `V= 6xx5xx4 = 120 m^(3)`. We can determine the number of mole. At room temperature 300K, the volume of a gas occupicd by any gas is equal to 24.6 L. The number of mole
`mu=(120m^(3))/(24.6xx10^(-3)m^(3))~~"4878 mol"`
Air is the mixture of about `20%` oxygen, `79%` nitrogen and remaining one percent are argon, hydrogen, helium and xenon. The molar mass mass of air is `"29 g mol"^(-1)`. So the total mass of air in the room `m=4878xx29xx10^(-3)=141.4kg`