Answer is: <span>nuclear fission. </span>Fission is nuclear reaction<span> or a </span>radioactive decay<span> process in which the </span>nucleus of an atom splits, <span>resulting atoms are not the same </span>elements<span> as the original atom</span>. The fission reaction<span> releases large amount of </span>energy. <span>Nuclear fission was discovered on 1938.</span>
