Answer: Option (a) is the correct answer.
Explanation:
It is known that an atom consists of three sub-atomic particles which are protons, neutrons, and electrons.
When an atom splits then only neutrons and protons are involved and no electrons are involved into the reaction.
Hence, energy is released by the nucleus of the atom. And, these type of reactions reactions are known as nuclear reactions.
For example, [tex]^{16}_{8}O + ^{1}_{1}n \rightarrow ^{13}_{7}N + ^{4}_{2}He[/tex]
Whereas isotopes are the species which have same atomic number but different mass number.
Thus, we can conclude that when atoms are split, from nucleus of the atom is the energy released.
