A hydrogen ion (H+) has only one subatomic particle, a(n) ______.

• A. proton
• B. positron
• C. neutron
• D. electron

Answer: (A)

Verified step by step guidance

1. Recall that a hydrogen ion (H+) is formed when a hydrogen atom loses an electron.
2. Understand that a hydrogen atom consists of one proton and one electron, and no neutrons in its most common isotope.
3. When the electron is removed, the remaining particle is just the proton.
4. Therefore, the hydrogen ion (H+) contains only one subatomic particle, which is a proton.
5. Review the definitions of other subatomic particles: a positron is the antimatter counterpart of an electron, a neutron has no charge, and an electron is negatively charged, so none of these fit the description of H+.