Answer:
Place two of them as reactants.
Step-by-step explanation:
- We have the two steps of reactions:
1) N₂(g ) + O₂(g) → 2NO(g).
2) 2NO(g )+ O₂(g) → 2NO₂(g).
- Adding the two equation with cancelling the intermediate (NO), we get:
N₂(g ) + 2O₂(g) → 2NO₂(g).
NO is cancelled out because there is one in each equation in the products side in eq. 1 and in oriduct side in eq. 2.
So, we place two of oxygen as reactants.