Given a scientific passage and an answer, generate a question for the given answer.
Q: Passage: In beta decay, an electron and a proton form from a neutron (another unusual particle, called an antineutrino, is also produced). Only the electron is emitted from the nucleus. How does this change the atomic number and atomic mass of the atom?. Answer: electron and a proton
A:
What particles are formed from a neutron in beta decay?