What type of particle is identical to an electron and emitted from the nucleus?

The correct answer is the beta particle, which is indeed identical to an electron in terms of charge and mass. A beta particle is emitted from the nucleus during the process of beta decay, where a neutron is transformed into a proton, resulting in the release of an electron (or beta particle) along with an antineutrino. This transformation maintains the conservation of charge, as the electrical charge of the released beta particle offsets the increase in positive charge from the added proton.

In contrast, alpha particles consist of two protons and two neutrons; gamma rays are high-energy electromagnetic radiation emitted from the nucleus without any mass or charge; and neutrons are neutral particles found in the nucleus itself, but they do not have the same properties as electrons or beta particles. Therefore, beta particles are the only ones that fit the description of being identical to an electron and emitted from the nucleus.