Binding Energy Per Nucleon Curve
On the curve of binding energy per nucleon plotted against mass number, one element sits at the peak and represents the most stable nuclear configuration. Which of the following nuclei lies closest to that maximum?
Select the correct option:
Solution
Iron-56
The binding energy per nucleon measures how tightly each nucleon is bound, and the higher this value, the more stable the nucleus. When plotted against mass number, the curve rises steeply for light nuclei, reaches a broad maximum of about 8.8 MeV per nucleon near mass number 56, and then declines gently for heavier nuclei. Iron-56 sits essentially at this peak, making it among the most stable of all nuclei. Hydrogen-2 (deuterium) has a very low binding energy per nucleon of only about 1.1 MeV, placing it far down the rising part of the curve. Uranium-238 lies well past the peak on the descending side at roughly 7.6 MeV per nucleon, which is why it can release energy by fission. Helium-4, though locally stable, peaks near 7 MeV per nucleon, still below iron. This is the classic NCERT binding-energy curve. A plausibility check confirms that elements near iron neither readily fuse nor fission to release energy, consistent with occupying the curve's maximum.
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About This Question
- Subject
- physics
- Chapter
- atoms and nuclei
- Topic
- binding energy per nucleon curve
- Difficulty
- Easy
- Year
- 2025
Solution
Correct Answer:
Iron-56
The binding energy per nucleon measures how tightly each nucleon is bound, and the higher this value, the more stable the nucleus. When plotted against mass number, the curve rises steeply for light nuclei, reaches a broad maximum of about 8.8 MeV per nucleon near mass number 56, and then declines gently for heavier nuclei. Iron-56 sits essentially at this peak, making it among the most stable of all nuclei. Hydrogen-2 (deuterium) has a very low binding energy per nucleon of only about 1.1 MeV, placing it far down the rising part of the curve. Uranium-238 lies well past the peak on the descending side at roughly 7.6 MeV per nucleon, which is why it can release energy by fission. Helium-4, though locally stable, peaks near 7 MeV per nucleon, still below iron. This is the classic NCERT binding-energy curve. A plausibility check confirms that elements near iron neither readily fuse nor fission to release energy, consistent with occupying the curve's maximum.
This easy difficulty physics question is from the chapter atoms and nuclei, covering the topic of binding energy per nucleon curve. It appeared in the 2025 exam.
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