Answer: The Coulomb barrier surrounding the nucleus.
- A The nucleus itself, as though it tunneled through its own point of origin
- B The Coulomb barrier surrounding the nucleus
- C The surrounding electron cloud orbiting around the parent atom
- D A magnetic confinement barrier generated by the nuclear spin
Correct answer: B. The Coulomb barrier surrounding the nucleus
Explanation: Alpha decay: alpha particle trapped inside but quantum tunnels through the Coulomb potential barrier. Gamow theory explains the wide range of half-lives.
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.