In the chemical formula H2O, what does the subscript 2 indicate?

• A. There Are Two Oxygen Atoms
• B. There Are Two Total Atoms
• C. There Are Two Hydrogen Atoms
• D. There Are Two Bonds

Answer: (C)

The subscript shows how many atoms of that element are in each molecule. In H2O, the hydrogen has a subscript of 2, so there are two hydrogen atoms in every water molecule. The oxygen has no subscript, which means there is one oxygen atom. That’s why water is made of two hydrogens and one oxygen. The total number of atoms is three, not two, so the subscript isn’t about total atoms, and it isn’t about bonds.