How many atoms of oxygen are present in one molecule of oxygen gas (O_2)?

• A. 2
• B. 3
• C. 1
• D. 4

Answer: (A)

Verified step by step guidance

1. Identify the chemical formula of oxygen gas, which is given as O_2. This means each molecule consists of oxygen atoms bonded together.
2. Understand that the subscript number in a chemical formula indicates the number of atoms of that element in one molecule. In O_2, the subscript '2' tells us there are two oxygen atoms.
3. Recognize that if there is no subscript number, it implies there is only one atom of that element in the molecule. Here, the subscript is explicitly '2', so it is not one atom.
4. Therefore, the number of oxygen atoms in one molecule of oxygen gas (O_2) is equal to the subscript number, which is 2.
5. Conclude that the correct answer to the question is 2 atoms of oxygen per molecule of O_2.