How does the nucleus change in beta-plus decay?

AThe mass number decreases by one, and the atomic number remains the same.
BThe mass number increases by one, and the atomic number remains the same.
CThe mass number remains the same, and the atomic number decreases by one.
DThe mass number remains the same, and the atomic number increases by one.

In beta-plus decay, the mass number remains the same while the atomic number decreases by one due to the conversion of a proton into a neutron. This transformation results in the emission of a positron and a neutrino. For example, carbon-11 decaying into boron-11 exemplifies this process.

Explanation:

Understanding Beta-Plus Decay

In beta-plus decay, a nucleus undergoes a transformation where a proton is converted into a neutron, emitting a positron (the beta particle) and a neutrino. This results in a change in the composition of the nucleus, specifically affecting the atomic number and the mass number.

To summarize the changes:

The mass number remains the same because the total number of nucleons (protons and neutrons) does not change. This is because a proton is transformed into a neutron, which does not add to or take away from the total count.
The atomic number decreases by one because the nucleus loses one proton. This decay process effectively changes the element into another element that is one position lower in the periodic table.

For example, when carbon-11 (with 6 protons) undergoes beta-plus decay, it transforms into boron-11 (with 5 protons), illustrating this concept perfectly.

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