Final answer:
The two particles most similar in mass are the proton and the neutron, with masses of approximately 1.0073 amu and 1.0087 amu, respectively. Therefore correct answer is option C.
Step-by-step explanation:
The question asks which two subatomic particles, out of a proton, an electron, and a neutron, have the most similar mass. The answer is C) the proton and the neutron. A proton has a mass of approximately 1.0073 amu (atomic mass units) with a positive charge, while a neutron has a mass of about 1.0087 amu and no charge, making their masses very similar.
In contrast, an electron has a much smaller mass of approximately 0.00055 amu with a negative charge. Therefore, considering the mass, protons and neutrons are substantially more similar to each other than either is to an electron, which has a significantly lighter mass.
It's worth noting that both the proton and the neutron are often referred to collectively as nucleons because they both reside in the nucleus of an atom. Electrons, having a negligible mass in comparison, do not contribute significantly to the overall mass of an atom. Because protons and neutrons constitute the bulk of an atom's mass, they're crucial for determining the atom's weight and, subsequently, the characteristics of different elements.