Arrange the following nuclei in increasing order of their binding energies per nucleon.
A. \( {}^{3}\mathrm{H} \)
B. \( {}^{4}\mathrm{He} \)
C. \( {}^{12}\mathrm{C} \)
D. \( {}^{56}\mathrm{Fe} \)
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → A, B, C, D
The binding energy per nucleon rises steeply for light nuclei, has a broad maximum of about 8.8 MeV near \( A = 56 \) (iron) and then falls slowly. Approximate values:
(A) \( {}^{3}\mathrm{H} \): about \( 2.8\,\mathrm{MeV} \)
(B) \( {}^{4}\mathrm{He} \): about \( 7.1\,\mathrm{MeV} \)
(C) \( {}^{12}\mathrm{C} \): about \( 7.7\,\mathrm{MeV} \)
(D) \( {}^{56}\mathrm{Fe} \): about \( 8.8\,\mathrm{MeV} \)
Increasing order: A, B, C, D.
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 \( (30 \lt A \lt 170) \). 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 \( (A \lt 30) \) and heavy nuclei \( (A \gt 170) \).”
