Which of the following is true of an oxygen atom that has 8 protons?

• A. It is an isotope of nitrogen.
• B. It must have 16 neutrons.
• C. It must also have 8 electrons if it is neutral.
• D. It has an atomic number of 16.

Answer: (C)

Verified step by step guidance

1. Recall that the atomic number of an element is defined by the number of protons in its nucleus. For oxygen, the atomic number is 8, meaning it has 8 protons.
2. Understand that isotopes are atoms of the same element (same number of protons) but with different numbers of neutrons. Since nitrogen has 7 protons, an oxygen atom cannot be an isotope of nitrogen.
3. Recognize that the number of neutrons in an oxygen atom can vary, leading to different isotopes (e.g., oxygen-16, oxygen-17, oxygen-18). Therefore, it does not have to have exactly 16 neutrons.
4. For an atom to be electrically neutral, the number of electrons must equal the number of protons. Since this oxygen atom has 8 protons, it must also have 8 electrons if it is neutral.
5. Confirm that the atomic number of oxygen is 8, not 16, so the statement about having an atomic number of 16 is incorrect.