Arrange the binding energy per nucleon of the following nuclei in ascending order:
A. \( {}^{14}\mathrm{N} \)
B. \( {}^{4}\mathrm{He} \)
C. \( {}^{32}\mathrm{S} \)
D. \( {}^{6}\mathrm{Li} \)
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → D, B, A, C
The binding energy per nucleon rises steeply for light nuclei, reaches about 8.8 MeV near \( A = 56 \), and then falls slowly. \( {}^{4}\mathrm{He} \) is an exception: it is unusually tightly bound for its mass.
D — \( {}^{6}\mathrm{Li} \): about 5.3 MeV per nucleon;
B — \( {}^{4}\mathrm{He} \): about 7.1 MeV per nucleon;
A — \( {}^{14}\mathrm{N} \): about 7.5 MeV per nucleon;
C — \( {}^{32}\mathrm{S} \): about 8.5 MeV per nucleon.
So the ascending order is D, B, A, C.
NCERT (2026-27):
Nuclear Binding Energy – “… 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. We notice the following main features of the plot: (i) the binding energy per nucleon, \( E_{bn} \), is practically constant, i.e. practically independent of the atomic number for nuclei of middle mass number \( (30 \lt A \lt 170) \). … (ii) \( E_{bn} \) is lower for both light nuclei \( (A \lt 30) \) and heavy nuclei \( (A \gt 170) \).”
