one electron would be added the atomic number would change the total mass of the atom would decrease the electrical charge would become neutral
I gave my students this multiple choice question: What would be the result of adding one proton to an atom?

Only one answer is correct among these 4 choices:
- one electron would be added
- the atomic number would change
- the total mass of the atom would decrease
- the electrical charge would become neutral

Could you tell me which one is correct?

the atomic number would change