How would you write 2 molecules of Oxygen and 5 molecules of Nitrogen ?

Explanation

2 molecules of oxygen `to` `2O_2` Reason :
1) Oxygen is diatomic element.
2) Two oxygen atoms combine to form one oxygen molecule.
3) The formula of oxygen molecule is `O_2`,
5 molecules of nitrogen `to` `5N_2`
Reason:
1) Nitrogen is also diatomic element.
2) Two nitrogen atoms combine to form one nitrogen molecule.
3) Molecular formula of nitrogen is `N_2`.