Answer : 51.8 g of nitrogen are needed to produce 100 grams of ammonia gas.
Solution : Given,
Mass of
= 100 g
Molar mass of
= 27 g/mole
Molar mass of
= 28 g/mole
First we have to calculate moles of
.

The given balanced chemical reaction is,

From the given reaction, we conclude that
2 moles of
produced from 1 mole of 
3.7 moles of
produced from
of 
Now we have to calculate the mass of
.
Mass of
= Moles of
× Molar mass of 
Mass of
= 1.85 mole × 28 g/mole = 51.8 g
Therefore, 51.8 g of nitrogen are needed to produce 100 grams of ammonia gas.