Final answer:
The source of energy emitted in radioactive decay is the conversion of a fraction of the original mass. The conservation law of mass-energy was modified to take into account this process.
Step-by-step explanation:
The source of the energy emitted in radioactive decay is the conversion of a fraction of the original mass of the decaying particle. This is due to the conservation of mass-energy, which was an earlier conservation law.
The conservation law was modified to take into account the energy produced in radioactive decay, which comes from the conversion of mass into energy. The general relationship is given by the equation E = ▲mc², where E is the nuclear reaction energy and ▲m is the difference in mass between the initial and final products.