Humber Admissions Practice Test 2025 - Free Practice Questions and Study Guide for Humber College Admissions

The three main types of subatomic particles are protons, neutrons, and electrons. Protons are positively charged particles found within the nucleus of an atom, and they determine the atomic number and, thus, the element's identity. Neutrons are neutral particles that also reside in the nucleus and contribute to the atomic mass of an atom. Electrons are negatively charged particles that orbit the nucleus and play a crucial role in chemical bonding and interactions.

This answer highlights the fundamental nature of these particles and how they come together to form atoms, which are the building blocks of matter. The other options introduce terms like isotopes, atomic number, molecules, and atoms, which do not accurately describe the three main subatomic particles themselves. Instead, isotopes refer to variants of elements with different neutron counts, atomic number quantifies the number of protons, and molecules refer to chemical combinations of atoms. Thus, the choice identifying protons, neutrons, and electrons as the three main subatomic particles is correct, as they are essential components of all atoms.