Question

which change to an atom occurs during a nuclear fission reaction? (1 point) the atomic number must change, but the mass number cannot. the atomic number cannot change, but the mass number must change. both the atomic number and the mass number must change. neither the atomic number nor the mass number can change. check answer remaining attempts : 3

Explanation:

Nuclear fission is a process where a heavy nucleus splits into smaller nuclei. The atomic number (number of protons) and mass number (sum of protons and neutrons) change because new elements (with different proton counts) and smaller nuclei (with different proton - neutron sums) are formed. For example, uranium - 235 ($U - 235$, atomic number $92$, mass number $235$) can split into krypton ($Kr$, atomic number $36$) and barium ($Ba$, atomic number $56$) along with neutrons. The atomic numbers of $U$, $Kr$, and $Ba$ are different, and the mass numbers of the products ($Kr$, $Ba$, and neutrons) sum up differently from the mass number of $U - 235$.

Answer:

Both the atomic number and the mass number must change.