What is the mass of a water molecule, O, in atomic mass units?

Question

What is the mass of a water molecule,  O, in atomic mass units?

Quizplus · Accepted Answer

The molecular formula for water is H2O. The atomic mass of hydrogen is approximately 1 amu, and there are two hydrogen atoms in water, so the total mass of the hydrogen atoms in water is approximately 2 amu. The atomic mass of oxygen is approximately 16 amu, and there is one oxygen atom in water, so the total mass of the oxygen atom in water is approximately 16 amu. Therefore, the mass of a water molecule is approximately 18 amu (2 amu + 16 amu). Therefore, the best choice is D, which is 18 amu.

What Is the Mass of a Water Molecule, O