Which subatomic particle has the lightest mass?

• A. Alpha particle
• B. Electron
• C. Proton
• D. Neutron

Answer: (B)

Verified step by step guidance

1. Recall the three main subatomic particles: electron, proton, and neutron, and understand that an alpha particle is a cluster of two protons and two neutrons.
2. Identify the relative masses of each particle: electrons have a much smaller mass compared to protons and neutrons.
3. Note that protons and neutrons have masses close to 1 atomic mass unit (amu), while electrons have a mass approximately 1/1836 of a proton.
4. Understand that an alpha particle, being composed of protons and neutrons, has a mass roughly four times that of a proton.
5. Conclude that among the given options, the electron has the lightest mass.