Final answer:
A molecule of water, which has the chemical formula H₂O, consists of 2 atoms of hydrogen and 1 atom of oxygen, making option 2 the correct answer.
Step-by-step explanation:
To answer the question regarding how many atoms of hydrogen and oxygen are there in a molecule of water, we need to consider water's chemical formula, which is H₂O. This formula indicates that each molecule of water consists of 2 atoms of hydrogen and 1 atom of oxygen. Thus, the correct answer to the question is option 2: There are 2 atoms of hydrogen and 1 atom of oxygen in a molecule of water.
The relationship between moles and molar mass is crucial here. For instance, the molar mass of water (H₂O) is 18.0158 g/mol, which means one mole of water weighs approximately 18 grams. This figure is derived from the addition of the molar masses of hydrogen (2 x 1.0079 g/mol for the two hydrogen atoms) and oxygen (16.00 g/mol). By using Avogadro's number (6.022 × 10²³ units per mole), we can determine that one mole of water molecules contains exactly 2 moles of hydrogen atoms and 1 mole of oxygen atoms.