There are more hydrogen atoms in living organisms than any other atom, but oxygen is more abundant in terms of mass. Why is this statement true?

Hydrogen atoms are much lighter than oxygen atoms: one hydrogen atom has a mass of about 1 atomic mass unit, while one oxygen atom has a mass of about 16. So organisms can contain more hydrogen atoms, yet oxygen can contribute more total mass. The correct choice is “Hydrogen atoms have a lower mass than oxygen atoms.”

AI-written and checked against the verified answer.