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

• A. 0
• B. 1
• C. 2
• D. 3

Answer: (B)

Verified step by step guidance

1. Identify the chemical formula of the molecule given, which is H_2O for water.
2. Understand that the subscript number in a chemical formula indicates the number of atoms of that element in one molecule.
3. Look at the subscript next to oxygen (O) in H_2O. Since there is no subscript explicitly written after O, it means there is exactly one oxygen atom.
4. Recognize that the subscript '2' after H means there are two hydrogen atoms, but this does not affect the count of oxygen atoms.
5. Conclude that one molecule of water contains exactly one oxygen atom.