A molecule of water is composed of two atoms of hydrogen andone atom of oxygen (H20). If the atomic mass number ofhydrogen is 1 and the molecular mass of water is 18, the atomicmass of oxyen must be (a)36 (c) 18 (b)16 (d)14 A molecule of water is composed of two atoms of hydrogen andone atom of oxygen (H20). If the atomic mass number ofhydrogen is 1 and the molecular mass of water is 18, the atomicmass of oxyen must be (a)36 (c) 18 (b)16 (d)14