$7 g$ of nitrogen occupies a volume of 5 liters under certain conditions. Under the same conditions one mole of a gas, having molecular weight 56, occupies a volume of _________ L.

Given mass of nitrogen is 7 g and the molecular mass of nitrogen gas is 28 g.

The number of moles of nitrogen = $\frac{7}{28}=0.25$

So, we can say that 0.25 moles of nitrogen occupies 5 liters of volume. Hence, 1 mole of nitrogen will occupies:

$\frac{5}{0.25}=20 L$

Therefore, 1 mole of nitrogen gas will occupy 20 L of volume.