Which of the following is NOT a fundamental subatomic particle that forms elements?

• A. Photon
• B. Electron
• C. Proton
• D. Neutron

Answer: (A)

Verified step by step guidance

1. Step 1: Understand what fundamental subatomic particles are. These are particles that make up atoms, which in turn form elements. The main subatomic particles involved in forming elements are protons, neutrons, and electrons.
2. Step 2: Recall the roles of each particle: Protons determine the element's identity (atomic number), neutrons contribute to the atomic mass and stability, and electrons are involved in chemical bonding and reactions.
3. Step 3: Identify what a photon is. A photon is a particle of light or electromagnetic radiation, not a constituent of atoms or elements.
4. Step 4: Compare the options given: Electron, Proton, and Neutron are all fundamental subatomic particles forming elements, while Photon is not part of the atomic structure.
5. Step 5: Conclude that the particle which is NOT a fundamental subatomic particle forming elements is the Photon.