Final answer:
The nucleus of an atom a) contains most of the mass of the atom.
Step-by-step explanation:
The experimental evidence indicates that the nucleus of an atom a) contains most of the mass of the atom. The nucleus is composed of protons and neutrons. Protons carry a positive charge and neutrons have no charge. These particles are packed together into an extremely small space at the center of an atom, making up most of its mass.
The nucleus of an atom contains protons and neutrons, serving as its central core. Its primary functions include providing the mass of the atom, determining its identity through the number of protons, and contributing to an overall stability of the atom. Nuclear reactions within the nucleus release energy, as seen in nuclear power.