Which of the following is the smallest particle?

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

Answer: (C)

Verified step by step guidance

1. Understand the basic structure of matter: Atoms are composed of three main subatomic particles—protons, neutrons, and electrons.
2. Recall the relative sizes and masses of these particles: Protons and neutrons have similar masses and are located in the nucleus, while electrons are much lighter and orbit the nucleus.
3. Recognize that the term 'smallest particle' here refers to the particle with the smallest mass and size among the options given.
4. Compare the particles: Protons and neutrons are roughly 1 atomic mass unit (amu) each, whereas electrons have a mass approximately 1/1836 that of a proton, making them significantly smaller.
5. Conclude that among the options (proton, neutron, electron, atom), the electron is the smallest particle.