Answer :
An atom bomb explode by initiating a nuclear chain reaction, which releases a huge amount of energy relative to conventional explosives. Per unit volume, an atom bomb may be millions or billions of times more powerful than TNT....................
When a neutron strikes the nucleus of an atom of the isotopes uranium 235 orplutonium-239, it causes that nucleus to split into two fragments, each of which is a nucleus with about half the protons and neutrons of the original nucleus. In the process of splitting, a great amount of thermal energy, as well as gamma rays and two or more neutrons, is released. Under certain conditions, the escaping neutrons strike and thus fission more of the surrounding uranium nuclei, which then emit more neutrons that split still more nuclei. This series of rapidly multiplying fissions culminates in a chain reaction in which nearly all the fissionable material is consumed, in the process generating the explosion of what is known as an atomic bomb.