Q: What happens to the mass number during a nuclear decay process by positron emission?


Read this paragraph and choose the correct option from the provided answers:

During a nuclear decay process that occurs by positron emission, a proton is converted into a neutron and a positron. The neutron remains in the nucleus, and the positron is expelled. Overall, the atomic number of the parent nucleus increases by one, and the mass number is unchanged. For example, carbon-11 emits a positron to become boron-11:.

 Choices:

- it rises

- it decreases

- it increases

- remains unchanged


A:
remains unchanged