Nuclear fission is the process in nuclear physics in which the nucleus of an atom splits into two daughter nuclei.
An example of nuclear fission is the splitting of Uranium-235. The equation of the reaction has been given below:
Nuclear fusion is when two or more atomic nuclei fuse to form a single heavier nucleus. In the reaction, the matter is not conserved because some of the mass of the fusing nuclei is converted to energy.
Fission obtains energy by splitting big atoms like plutonium into lighter atoms like iodine, cesium, strontium, xenon, and barium.
Fusion, on the other hand, uses light atoms like deuterium and tritium, two hydrogen isotopes, to produce heavier helium.
Modern nuclear weapons are made possible by a combination of chemical explosives, nuclear fission, and nuclear fusion.
Fission releases a substantial amount of energy in the form of X-rays, which leads to the high temperature and pressure required to start fusion.
Nuclear fuel is compressed by the explosions, which causes fission.