Assuming the volume of the gas is measured at standard temperature and pressure, Then one mole of the Gas would occupy 22.4 liters.
Therefore, 1 liter is 1/224 moles
one mole of nitrogen 14 is 14
Therefore 1 liter of the nitrogen weighs 1/224×14
0.0625 grams
The formula of density is mass / volume
This means that
- high mass, low volume = high density
- high mass, high volume = so-so
- low mass, high volume = low density
From the graph shown,
D has the lowest density because it has low mass yet high volume.