A Level Physics Practice Exam

Which particles are found in the nucleus of an atom?

1. Electrons and protons

2. Protons and neutrons

3. Neutrons and electrons

4. Neutrons, protons, and electrons

The correct answer is: Protons and neutrons

The nucleus of an atom is comprised primarily of protons and neutrons. Protons are positively charged particles, and their number determines the atomic number of an element, while neutrons, which have no charge, contribute to the mass of the nucleus. Together, protons and neutrons make up the nuclear mass and are held together by the strong nuclear force, which is essential for the stability of the atom. Electrons, on the other hand, do not reside in the nucleus; they exist in electron shells or energy levels surrounding the nucleus. They have a negative charge and are involved in chemical bonding and reactions but do not contribute to the mass of the nucleus. Thus, the correct choice accurately reflects the particles that inhabit the nucleus, confirming that protons and neutrons are the fundamental components that define its structure. Other options incorrectly include electrons, which are not part of the nucleus.