Hydrogen + Nitrogen

Hydrogen + Nitrogen ➜ Ammonia
3H₂ + N₂ ➜ 2NH₃

molecular weights
H = 1.008
N = 14.006
3H₂ = 6.048
N₂ = 2•14.006 = 28.012
2NH₃  = 34.06
3 mole of H₂ + 1 moles of N₂ ➜ 2 moles of NH₃
6.048 grams of H₂ + 28.012 grams of N₂ ➜ 34.06 grams of NH₃



Following two are theoretical only
Nitrogen + Oxygen --> Dinitrogen Pentaoxide
but this is not a possible reaction.
2N₂ + 5O₂ --> 2N₂O₅
or
4•14 g of N₂ + 10•16 g of O₂ --> 2•108 g ot N₂O₅

4NO₂ + O₂ --> 2N₂O₅