Answer: Protons and neutrons.
- A Mainly protons
- B Mainly neutrons
- C Protons and neutrons
- D Electrons and protons
Correct answer: C. Protons and neutrons
Explanation: The nucleus contains protons (positive) and neutrons (neutral), collectively called nucleons.
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.