Which of the following is the molar mass of H_2O?

• A. 20.02 g/mol
• B. 18.02 g/mol
• C. 2.02 g/mol
• D. 16.00 g/mol

Answer: (B)

Verified step by step guidance

1. Identify the elements present in the compound H_2O, which are hydrogen (H) and oxygen (O).
2. Determine the number of atoms of each element in one molecule of H_2O: there are 2 hydrogen atoms and 1 oxygen atom.
3. Find the atomic masses of hydrogen and oxygen from the periodic table: approximately 1.01 g/mol for hydrogen and 16.00 g/mol for oxygen.
4. Calculate the total mass contributed by hydrogen atoms: multiply the atomic mass of hydrogen by the number of hydrogen atoms, i.e., \$2 \times 1.01$ g/mol.
5. Add the mass of hydrogen atoms to the atomic mass of oxygen to get the molar mass of H_2O: \( (2 \times 1.01) + 16.00 \) g/mol.