is nitrogen gas lighter than air
Nitrogen gas is less dense than air. Nitrogen is lighter than air because it has a lower density than air. The density of #N_2# gas at STP is #1.2056 kg/m^3#, and the density of air at STP is #1.293 kg/m^3#. So, there is less mass of #N_2# per cubic meter, and a greater mass of air per cubic meter.