Given below are two statements: one is labelled Assertion (A) and the other is labelled Reason (R).
Assertion (A): For the same quantity of matter, a chemical source produces a million times more energy than a nuclear source.
Reason (R): The energies involved in nuclear reactions are of the order of MeV.
Choose the correct answer from the options given below.
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → (A) is false but (R) is true.
Assertion (A) For the same quantity of matter, a chemical source produces a million times more energy than a nuclear source. — False. A nuclear source produces about a million times more energy than a chemical source. Fission of 1 kg of uranium gives about \( 10^{14}\,\mathrm{J} \). Burning 1 kg of coal gives only about \( 10^{7}\,\mathrm{J} \).
Reason (R) The energies involved in nuclear reactions are of the order of MeV. — True. The energy released in a nuclear reaction is of the order of MeV. Exothermic chemical reactions, such as the burning of coal or petroleum, involve energies of only a few electron volts.
NCERT (2026-27):
Nuclear Energy – “Exothermic chemical reactions underlie conventional energy sources such as coal or petroleum. Here the energies involved are in the range of electron volts. On the other hand, in a nuclear reaction, the energy release is of the order of MeV. Thus for the same quantity of matter, nuclear sources produce a million times more energy than a chemical source.”