If a certain number of neutrons and protons are brought together to form a nucleus, a fixed amount of energy \( E_b \) is associated with it. What happens to this energy in the process?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → It is released.
Option (1) It is absorbed from the surroundings. — Incorrect. Energy has to be supplied only to separate a nucleus into its nucleons. Bringing the nucleons together gives energy out.
Option (2) It is converted into the mass of the nucleus. — Incorrect. The nucleus formed is lighter than its separate nucleons. Its mass is less than theirs by the mass defect \( \Delta M \).
Option (3) No energy change takes place. — Incorrect. The nuclear mass is always less than the total mass of its protons and neutrons. This mass defect is equivalent to an energy \( \Delta M\,c^{2} \).
Option (4) It is released. — Correct. The bound nucleus has less mass-energy than its free nucleons, so the difference \( E_b=\Delta M\,c^{2} \), the binding energy, is released when the nucleus is formed.
NCERT (2026-27):
Nuclear Binding Energy – “If a certain number of neutrons and protons are brought together to form a nucleus of a certain charge and mass, an energy Eb will be released in the process. The energy Eb is called the binding energy of the nucleus. If we separate a nucleus into its nucleons, we would have to supply a total energy equal to Eb, to those particles.”