How many moles of hydrogen will be needed to react with 2 moles of nitrogen in the reaction #N_2 + H_2 -> NH_3#?
The balanced equation for dinitrogen reduction is:
The equation above represents probably the most important inorganic reaction on the planet in that it allows the formation of ammonia and nitrates for nitrogenous fertilizer.
Your question specified 2 moles of nitrogen. I would be quite justified in assuming that the questioner meant 2 moles of dinitrogen gas, i.e. the equivalent of