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⚛️ Physics  ·  Nuclei  ·  NEET & JEE

The semi-empirical mass formula (Bethe-Weizsacker) has terms for:

Answer: Volume, surface, Coulomb, asymmetry, and pairing.

  • A Volume, surface, Coulomb, asymmetry, and pairing
  • B Mainly the volume term and the surface term, with nothing else
  • C Mainly the Coulomb repulsion term, with little other contributions
  • D Just a single overall binding energy term with little further structure

Correct answer: A. Volume, surface, Coulomb, asymmetry, and pairing

Explanation: Semi-empirical formula: E<sub>B</sub> = a<sub>V</sub> A - a<sub>S</sub> A<sup>2/3</sup> - a<sub>C</sub> Z(Z-1)/A<sup>1/3</sup> - a<sub>A</sub> (A-2Z)²/A ± delta (pairing). Five terms capture nuclear physics.

Binding Energy per Nucleon vs Mass NumberMass number ABE/nucleonFe-56 (peak, most stable)FUSION region (light → medium)FISSION region (heavy → medium)Both processes release energy by moving nuclei toward the Fe-56 peak

Binding energy per nucleon rises sharply for light nuclei, peaks around iron-56 (the most stable nucleus), then slowly declines for heavier nuclei - which is exactly why fusing light nuclei or splitting heavy nuclei both release energy: each moves the products toward this stability peak.

Concept context

Radioactivity, nuclear reactions, fission, fusion, and binding energy.

Read the full Nuclei notes →