Step-by-step explanation:
1) Reaction between nitrogen gas and oxygen gas.
![N_2(g)+O_2(g)\rightarrow 2NO(g)](https://img.qammunity.org/2020/formulas/chemistry/college/5o50tdhy9a6y5cz0jrapw3brximbfpj40m.png)
According to reaction, hen 1 mole nitrogen gas reacts with 1 mole of oxygen gas it forms nitrogen oxide gas as a product.
2)reaction between nitrogen oxide and oxygen gas.
![2NO(g)+O_2(g)\rightarrow 2NO_2(g)](https://img.qammunity.org/2020/formulas/chemistry/college/h89oqtcb0bv4a370blfbxj0v4f5b9o4p2s.png)
According to reaction , when 2 mole of nitrogen oxide reacts with 1 moles of oxygen gas to form 2 moles of nitrogen dioxide.