Arrange the nuclei of the following atoms in ascending order of their…

The correct answer is Option (2) → (A), (D), (C), (B)

Binding energy per nucleon measures how tightly each nucleon is held. It rises steeply for light nuclei, because a small nucleus has a large fraction of nucleons at the surface with fewer neighbours; ⁴He is an exception that stands unusually high because it is an especially stable, compact nucleus. The curve peaks at about 8.8 MeV near A = 56 and then falls slowly for heavy nuclei, because the Coulomb repulsion between the many protons grows.

    \( \text{(A) } {}^{6}\mathrm{Li}: \approx 5.3\,\mathrm{MeV} \)
    \( \text{(D) } {}^{4}\mathrm{He}: \approx 7.1\,\mathrm{MeV} \)
    \( \text{(C) } {}^{238}\mathrm{U}: \approx 7.6\,\mathrm{MeV} \)
    \( \text{(B) } {}^{12}\mathrm{C}: \approx 7.7\,\mathrm{MeV} \)

So the ascending order is (A), (D), (C), (B).

NCERT (2026-27):
Nuclear Binding Energy – “… We can think of binding energy per nucleon as the average energy per nucleon needed to separate a nucleus into its individual nucleons. Figure 13.1 is a plot of the binding energy per nucleon E_bn versus the mass number A for a large number of nuclei. … The curve has a maximum of about 8.75 MeV for A = 56 and has a value of 7.6 MeV for A = 238. (ii) E_bn is lower for both light nuclei (A<30) and heavy nuclei (A>170).”