When an atomic nucleus emits a beta particle, which of the following occurs?

• A. The atomic number remains unchanged.
• B. The mass number increases by 1.
• C. A neutron is converted into a proton, and the atomic number increases by 1.
• D. A proton is converted into a neutron, and the atomic number decreases by 1.

Answer: (C)

Verified step by step guidance

1. Understand what a beta particle is: a beta particle is an electron (\( \beta^- \)) emitted from the nucleus during beta decay.
2. Recall that beta decay involves the transformation of a neutron into a proton inside the nucleus, which emits a beta particle (electron) and an antineutrino.
3. Recognize that when a neutron converts into a proton, the atomic number (number of protons) increases by 1 because a new proton is formed.
4. Note that the mass number (total number of protons and neutrons) remains unchanged because a neutron is lost but a proton is gained, keeping the total nucleon count the same.
5. Conclude that the correct description of beta decay is: a neutron is converted into a proton, and the atomic number increases by 1, while the mass number stays the same.