In an atomic explosion, a large amount of energy is released due to the conversion of mass into energy. This phenomenon is described by Albert Einstein`s famous equation, E=mc^2, where E represents energy, m represents mass, and c represents the speed of light.
Option 1 suggests that the release of energy is due to the conversion of chemical energy into nuclear energy. However, in an atomic explosion, the energy released is not a result of chemical reactions but rather nuclear reactions, specifically nuclear fission or fusion.
Option 2 suggests that the release of energy is due to the conversion of nuclear energy into heat. While heat is a form of energy that is produced in an atomic explosion, it is not the primary source of the released energy. The main source of energy in an atomic explosion is the conversion of mass into energy.
Option 4 suggests that the release of energy is due to the conversion of chemical energy into heat. However, as mentioned earlier, the energy released in an atomic explosion is not a result of chemical reactions but rather nuclear reactions.
Therefore, the correct answer is option 3, which states that the release of a large amount of energy in an atomic explosion is due to the conversion of mass into energy.