In which part of the atom do electrons reside?

Electrons reside in the electron cloud, which is the region surrounding the nucleus of an atom. This cloud is not a physical structure but rather a zone where electrons are likely to be found, according to quantum mechanics. It represents the areas in which electrons orbit around the nucleus, akin to how planets orbit around the sun but in a probabilistic manner rather than defined paths.

In the nucleus, which contains protons and neutrons, there is no space for electrons. The other options, such as "proton shell" and "neutron field," do not correspond to any scientifically recognized terminology related to electron positions. The proton shell implies a structure that does not exist in atomic theory, while the neutron field suggests an area related to neutrons, which are neutral particles and do not influence where electrons are found. Thus, the electron cloud is fundamentally the correct area where electrons exist within an atom.