Beta minus decay is best described as which process?

• A. A neutron converts to a proton and emits a beta particle
• B. A proton converts to a neutron and emits a positron
• C. An alpha particle is emitted
• D. The nucleus captures an orbital electron

Answer: (A)

Beta minus decay involves a neutron in the nucleus transforming into a proton, with the emission of a beta particle (an electron) and an antineutrino. This increases the atomic number by one while keeping the mass number the same. So describing it as a neutron converting to a proton and emitting a beta particle captures the essential change in the nucleus. The other options refer to different processes: a proton turning into a neutron with a positron is beta plus decay; releasing an alpha particle is alpha decay; and capturing an orbital electron is electron capture.