When a nucleus in an atom undergoes a radioactive decay, the atomic number and/or mass number of the atom

Step-by-step solution

In decay, the atomic number decreases by 2 and the mass number decreases by 4 . In decay, the atomic number changes by 1 (increases in ⁻ and decreases in ⁺ ) while the mass number remains unchanged. In decay, neither the atomic number nor the mass number changes, as it only involves a transition between nuclear energy levels. Thus, the atomic number and/or mass number change for and radiations but not for radiation. Answer: change for and radiations but not for radiation.