Match List-I with List-II.
| List-I | List-II |
| (1) Atomic nucleus | (A) Nuclear fission |
| (2) Mass defect | (B) Nuclear fusion |
| (3) Joining of light nuclei | (C) Binding energy |
| (4) Breaking of a heavy nucleus | (D) Much smaller than the atom |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → 1-D, 2-C, 3-B, 4-A
(1) Atomic nucleus — This matches (D) Much smaller than the atom. Scattering of α-particles showed that the radius of a nucleus is about \( 10^{4} \) times smaller than that of the atom. Yet the nucleus holds more than 99.9% of the atom’s mass.
(2) Mass defect — This matches (C) Binding energy. A nucleus is lighter than its separated nucleons by \( \Delta M \). The equivalent energy \( E_b=\Delta Mc^2 \) is the binding energy. This energy must be supplied to pull the nucleons apart.
(3) Joining of light nuclei — This matches (B) Nuclear fusion. Two light nuclei fuse into a larger, more tightly bound nucleus, and energy is released. This happens in the stars.
(4) Breaking of a heavy nucleus — This matches (A) Nuclear fission. A heavy nucleus such as uranium-235, struck by a neutron, splits into two intermediate mass fragments and releases energy.
NCERT (2026-27):
Introduction – “… The overall dimensions of a nucleus are much smaller than those of an atom.”
Nuclear Binding Energy – “… This energy required Eb is related to the mass defect by”
\( E_b=\Delta M\,c^2 \qquad (13.8) \)
“… The energy Eb is called the binding energy of the nucleus.”
Nuclear Fusion – Energy Generation in Stars – “When two light nuclei fuse to form a larger nucleus, energy is released, since the larger nucleus is more tightly bound …”
Fission – “A most important neutron-induced nuclear reaction is fission. An example of fission is when a uranium isotope 23592U bombarded with a neutron breaks into two intermediate mass nuclear fragments”
\( {}^{1}_{0}\mathrm{n}+{}^{235}_{92}\mathrm{U}\rightarrow{}^{236}_{92}\mathrm{U}\rightarrow{}^{144}_{56}\mathrm{Ba}+{}^{89}_{36}\mathrm{Kr}+3\,{}^{1}_{0}\mathrm{n} \qquad (13.10) \)