Final answer:
Nuclear fusion, fission, and radioactive decay are all nuclear reactions, involving the transformation of the nucleus of an atom. Combustion is a chemical, not nuclear, process. Fusion combines nuclei, fission splits them, and radioactive decay sees a nucleus emit radiation.
Step-by-step explanation:
The nuclear reactions listed by a student are nuclear fusion, combustion, nuclear fission, and radioactive decay. Among these, fusion, fission, and radioactive decay are indeed considered to be nuclear reactions.
- Nuclear fusion is the process of combining two light atomic nuclei to form a heavier nucleus. An example of this process can be seen in the core of stars where hydrogen nuclei fuse to form helium.
- Nuclear fission is the splitting of a heavy atomic nucleus into lighter nuclei, often accompanied by the release of energy. This reaction is utilized in nuclear reactors and atomic bombs.
- Radioactive decay is a spontaneous process in which an unstable atomic nucleus loses energy by emitting radiation. This can result in the transformation of one element into another.
Unlike these, combustion is a chemical reaction that involves the oxidation of a substance and is not a nuclear reaction. Combustion deals with the electrons of an atom, whereas nuclear reactions involve changes to the atom's nucleus.