Answer:
It would become a different element.
Step-by-step explanation:
When you change the number of protons i.e, add a proton in the nucleus of an atom, you will change the atom from one element to a different element and also positive charge of the atom also increased by 1.
For example, adding a proton to the nucleus of an atom of hydrogen creates an atom of helium.
So, we conclude that by adding a proton the atom will change from one element to another element.