Which of the following subatomic particles has the lowest mass?

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

Answer: (B)

Verified step by step guidance

1. Recall the masses of the subatomic particles involved: the electron, proton, neutron, and alpha particle.
2. Understand that the electron is a fundamental particle with a much smaller mass compared to protons and neutrons, which are nucleons found in the atomic nucleus.
3. Note that an alpha particle consists of 2 protons and 2 neutrons, so its mass is roughly four times that of a proton or neutron.
4. Compare the masses: the proton and neutron have similar masses (about 1 atomic mass unit each), the alpha particle is about 4 atomic mass units, and the electron's mass is approximately 1/1836 of a proton's mass.
5. Conclude that among the given options, the electron has the lowest mass because it is much lighter than protons, neutrons, and alpha particles.