The answer is, "1 molecule of nitrogen reacts with 3 molecules of hydrogen to give 2 molecules of ammonia."
Considering the reaction:
N₂ + 3 H₂ ------> 2 NH₃.
As this can be seen from the reaction that, "1 molecule of nitrogen reacts with 3 molecules of hydrogen to give 2 molecules of ammonia."
So the answer is that "1 molecule of nitrogen reacts with 3 molecules of hydrogen to give 2 molecules of ammonia."