Step-by-step explanation:
Atomic mass is the total number of all the protons and neutrons present in an atom.
For example, a carbon atom has atomic number 6 and it has 6 neutrons.
Atomic number also means the total number of protons present in an atom.
Hence, atomic mass of this carbon atom will be (6 protons + 6 neutrons) = 12.
If two protons and two neutrons are added to the nucleus of a carbon atom then atomic mass of this carbon atom will be as follows.
Atomic mass = [(6 + 2) protons + (2 + 6) neutrons]
= 16
As it is known that oxygen is the element that has atomic mass 16 and atomic number 8.
Therefore, we can conclude that the nucleus of given carbon atoms has converted into the nucleus of oxygen atom.