What is the source of the energy emitted in radioactive decay? Identify an earlier conservation law, and describe how it was modified to take such processes into account.

According to the quantum theory, it is impossible to anticipate whether a certain atom will experience nuclear disintegration or radioactive decay.

The spontaneous emission of \({\rm{\alpha }}\)- particles, \({\rm{\beta }}\) particles or \({\rm{\gamma - }}\)radiation from the nuclei of some elements is called radioactivity. The emitted radiations are called nuclear radiation and the element emitting these radiations is called radioactive element.

During radioactivity there is destruction of unstable nuclei and this destruction leads to spontaneous emission of radiation. So source of energy emitted during radioactive decay is nucleus of the atom.

Earlier law of conservation of energy states that energy neither created nor destroyed but can be transformed into one form of energy to another form of energy. But in radioactivity emission of energy carrying radiation takes place without input of any external energy so here violation of law of energy takes place so for taking the process into account the law modified and states that energy of system remains conserved.

Therefore the source of radiation is Nucleus and Energy is conserved.