Of the following, which is the smallest particle in an atom?

Protons are positively charged particles found in the nucleus of an atom and have a relatively large mass of approximately 1 atomic mass unit (amu). They are much larger than electrons, making them one of the heavier components of an atom. As a fundamental building block of atomic structure, protons significantly contribute to the atomic mass, but they are not the smallest particles.

Neutrons are neutral particles located in the nucleus alongside protons. They have a mass similar to that of protons, approximately 1 amu, making them significantly larger than electrons. Neutrons contribute to the atomic mass but do not influence the atomic charge, and they are not the smallest particles in an atom.

The nucleus is the central core of an atom, composed of protons and neutrons. It contains most of the atom's mass but is not a particle itself; instead, it is a collection of particles. Since the nucleus is made up of larger particles (protons and neutrons), it is much larger than an electron.