Final answer:
In β decay, the atomic number increases by one due to a neutron converting to a proton, but the mass number remains unchanged. The correct answer is b) Increase in atomic number, no change in mass number.
Step-by-step explanation:
If a parent nuclide undergoes a β decay, one would expect the following to be true: the atomic number would increase while the mass number remains the same. Specifically, the correct answer is b) Increase in atomic number, no change in mass number. During β decay, a neutron in an atom's nucleus is converted into a proton and an electron. The electron is emitted as a β particle (beta particle), and the proton remains in the nucleus. This process leads to an increase in the atomic number by one since the number of protons, which defines the atomic number, has increased by one. However, because the neutron turns into a proton, the overall mass number, which is the total number of protons and neutrons, does not change. An example of β decay is 14C decaying into 14N, where carbon-14 (β emitter with 6 protons) converts to nitrogen-14 (7 protons) with the mass number remaining constant at 14.