How many oxygen atoms are present in one molecule of H_2O?

• A. 2
• B. 1
• C. 0
• D. 3

Answer: (B)

Verified step by step guidance

1. Identify the chemical formula of the molecule given, which is H_2O. This formula represents water.
2. Understand that the subscript number following an element symbol indicates the number of atoms of that element in one molecule.
3. In H_2O, the subscript '2' after H means there are 2 hydrogen atoms, and the absence of a subscript after O means there is 1 oxygen atom.
4. Therefore, count the oxygen atoms by noting the subscript for O, which is implicitly 1 when no number is shown.
5. Conclude that one molecule of H_2O contains exactly 1 oxygen atom.