NO refers to nitric oxide, a colorless gas that is involved in numerous biological processes. It is produced during the reaction of nitrogen and oxygen gases.
NO3 represents the nitrate ion, which consists of one nitrogen atom bonded to three oxygen atoms. It is often involved in redox reactions due to its ability to donate or accept electrons.
O2 represents molecular oxygen, which is a diatomic molecule consisting of two oxygen atoms bonded together. It is necessary for respiration and combustion processes.