History of nuclear science: the discovery of the phenomenon of radioactivity is credited to which scientist?

Introduction / Context:
Understanding milestones in nuclear science provides context for modern engineering applications. Radioactivity, the spontaneous emission from unstable nuclei, underpins nuclear energy, medical diagnostics, and radiation protection standards. Identifying who first discovered it is a staple general knowledge item.

Given Data / Assumptions:

• Question asks for the original discoverer of radioactivity.
• Several eminent physicists worked on related phenomena around the same time.
• No computation is involved.

Concept / Approach:
Henri Becquerel discovered natural radioactivity in 1896 while investigating phosphorescent uranium salts and their ability to fog photographic plates without exposure to sunlight. Marie and Pierre Curie subsequently isolated radioactive elements (polonium, radium) and advanced the field. Roentgen discovered X-rays (not radioactivity) in 1895, and J. J. Thomson identified the electron. Ernest Rutherford later characterized alpha and beta radiation and proposed the nuclear atom model, but he did not make the original discovery of radioactivity.

Step-by-Step Solution:
Recall chronology: Roentgen (X-rays, 1895) → Becquerel (radioactivity, 1896) → Curies (new radioactive elements).Match each scientist to their discovery.Select Henri Becquerel for radioactivity.

Verification / Alternative check:
Standard physics histories consistently credit Becquerel with the discovery and the Curies with subsequent isolation/exploration of strongly radioactive substances.

Why Other Options Are Wrong:
Marie Curie: Pioneered research and element isolation but did not first discover radioactivity.Roentgen: Discovered X-rays, a separate phenomenon.J. J. Thomson: Discovered the electron.Ernest Rutherford: Characterized radiation types and nuclear structure later.

Common Pitfalls:
Conflating X-rays with radioactivity or attributing the first discovery to the Curies due to their fame and contributions soon after Becquerel's findings.

Final Answer:
Henri Becquerel