Which statement best describes nuclear fusion?

Which statement best describes nuclear fusion?

• A. A heavy nucleus splits into two lighter nuclei
• B. Two light nuclei combine to form a heavier nucleus
• C. A light nucleus splits into a series of lighter particles
• D. A nucleus emits a gamma ray without changing its composition

Answer: (C)

Fusion is the process in which two light nuclei come close enough to fuse into a single heavier nucleus, releasing energy in the process. This release happens because the resulting nucleus has a higher binding energy per nucleon, so some mass is converted into energy (mass defect). In stars, hydrogen nuclei fuse to form helium, powering the sun, and scientists aim to achieve controlled fusion in the lab by reaching extremely high temperatures and pressures to overcome the electrostatic repulsion between positively charged nuclei. The other descriptions fit other nuclear processes: splitting a heavy nucleus into lighter pieces is fission, and emitting a gamma ray without changing the nucleus’s composition is a gamma transition, not fusion.

Fusion is the process in which two light nuclei come close enough to fuse into a single heavier nucleus, releasing energy in the process. This release happens because the resulting nucleus has a higher binding energy per nucleon, so some mass is converted into energy (mass defect). In stars, hydrogen nuclei fuse to form helium, powering the sun, and scientists aim to achieve controlled fusion in the lab by reaching extremely high temperatures and pressures to overcome the electrostatic repulsion between positively charged nuclei. The other descriptions fit other nuclear processes: splitting a heavy nucleus into lighter pieces is fission, and emitting a gamma ray without changing the nucleus’s composition is a gamma transition, not fusion.