Which subatomic particle is J. J. Thomson credited with discovering?

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

Answer: (A)

Verified step by step guidance

1. Recall the historical experiments conducted by J. J. Thomson, particularly his cathode ray tube experiments.
2. Understand that Thomson observed particles smaller than atoms that were negatively charged, which led to the discovery of a fundamental subatomic particle.
3. Identify that the particle discovered by Thomson is the electron, which carries a negative charge and is a component of atoms.
4. Recognize that photons are particles of light, protons are positively charged particles discovered later, and neutrons are neutral particles discovered after protons.
5. Conclude that J. J. Thomson is credited with discovering the electron.