How many hydrogen atoms are present in one molecule of water (H_2O)?

• A. 4
• B. 2
• C. 3
• D. 1

Answer: (B)

Verified step by step guidance

1. Identify the chemical formula of the molecule given, which is water (H_2O).
2. Understand that the subscript number after an element symbol indicates the number of atoms of that element in one molecule.
3. Look at the subscript for hydrogen (H) in H_2O, which is 2, meaning there are 2 hydrogen atoms in one molecule of water.
4. Note that the subscript for oxygen (O) is 1, but since it is not written explicitly, it is understood to be 1 atom of oxygen.
5. Conclude that the number of hydrogen atoms in one molecule of water is 2.