Master Canadian Nursing Abbreviations Practice

O2 represents oxygen, a diatomic molecule that we commonly use and breathe in our everyday lives. Option A, ozone, is a triatomic molecule which is an allotrope of oxygen, but it does not exclusively represent 'O2'. Option C, octane, is a compound used in gasoline and has no relation to oxygen. Option D, osmium, is a chemical element and does not represent 'O2'. Thus, option B, oxygen, is the only correct representation of 'O2'.