the number of valence electrons the charge of the compound the mass of protons in each atom the number of atoms of each element
I gave my students this multiple choice question: The chemical formula for water is H_{2}O. What does the formula show about each element in the compound?

Only one answer is correct among these 4 choices:
- the number of valence electrons
- the charge of the compound
- the mass of protons in each atom
- the number of atoms of each element

Could you tell me which one is correct?

the number of atoms of each element