The maximum amount of nitrogen that can be safely put in this container must, exert a pressure less than 2 atom at 298K. i.e. maximum moles in container n=
PV
RT
=
2×2.24
0.0821×298
=0.18 i. e. maximum weight of N2 in container = 0.183 × 28 = 5.127 gm. The correct answer is, (D) 4.2 grams for safety concern, we can’t go for adding more nitrogen.