In nuclear physics, the first clear indication that even a stable atomic nucleus can be broken down into smaller particles was provided by which scientist's experiments?

Introduction / Context:
This general chemistry and physics question focuses on the early history of nuclear science. It asks which scientist first provided experimental evidence that even a stable atomic nucleus can be broken down or disintegrated. Understanding this historical milestone helps you appreciate how our concept of the atom evolved from an indivisible unit to a complex system that can undergo nuclear reactions.

Given Data / Assumptions:

• The key idea is the first indication that a stable nucleus is not permanent and can be broken down.
• The options list important scientists: Ernest Rutherford, Madam Curie, Frederick Soddy, Schmidt and J. J. Thomson (in corrected form).
• Radioactivity itself was known from Becquerel and the Curies, but the question is about deliberate or clear nuclear disintegration of a stable nucleus.
• We assume standard textbook history of atomic structure and nuclear transmutation.

Concept / Approach:
Natural radioactivity, discovered by Becquerel and studied extensively by the Curies and Soddy, showed that some nuclei are unstable and break down spontaneously. However, the idea that a stable nucleus can be forced to disintegrate by bombardment was first demonstrated in Rutherford experiments. By firing alpha particles at nitrogen, Rutherford observed the emission of protons and formation of a different nucleus. This was the first artificial nuclear reaction and a direct indication that even a stable nucleus can be broken apart under suitable conditions.

Step-by-Step Solution:
1) Becquerel and the Curies discovered spontaneous radioactivity, which involves naturally unstable nuclei but does not directly show that stable nuclei can be broken by external means.2) Frederick Soddy worked with radioactivity and transmutation concepts, but he did not perform the first clear artificial disintegration of a stable nucleus.3) J. J. Thomson studied cathode rays and discovered the electron, focusing on atomic structure outside the nucleus.4) Rutherford carried out famous alpha particle bombardment experiments, including the scattering experiment that led to the nuclear model of the atom.5) In additional work, Rutherford bombarded nitrogen gas with alpha particles and observed ejection of hydrogen nuclei (protons), effectively transforming nitrogen into oxygen. This nuclear reaction showed that a stable nitrogen nucleus can be broken down.6) Therefore, Rutherford experiments provided the first clear indication that a stable nucleus could be disintegrated, making him the correct answer.

Verification / Alternative check:
Standard nuclear chemistry history describes the reaction: 14N + alpha → 17O + proton. Here, the nitrogen nucleus captures an alpha particle and emits a proton, changing into oxygen. This was the first convincingly demonstrated artificial nuclear transmutation. Although the Curies and Soddy discussed transmutation, they studied natural decay of already unstable elements. Rutherford was the scientist who experimentally forced a stable nucleus to change, demonstrating that the nucleus is not indestructible and can be deliberately broken down.

Why Other Options Are Wrong:
Madam Curie: She discovered and studied radioactive elements like radium and polonium, but her work focused on natural radioactivity, not the artificial breaking up of stable nuclei.
Frederick Soddy: He explained disintegration series and isotopes but did not perform the first artificial disintegration of a stable nucleus.
Schmidt: Also worked with early observations of radioactivity but is not credited with the first deliberate nuclear disintegration of a stable nucleus.
J. J. Thomson: Discovered the electron and the e/m ratio, which advanced atomic theory but did not involve destruction of the atomic nucleus.

Common Pitfalls:
Many students confuse the discovery of radioactivity with the first artificial nuclear reaction. It is important to distinguish between spontaneous decay of unstable nuclei and deliberate bombardment that breaks a stable nucleus. Another common error is to choose the Curies because of their fame in radioactivity, but the specific achievement asked here is Rutherford nuclear disintegration of nitrogen, which is a separate historical step. Keeping a simple timeline in mind helps: Becquerel and the Curies for natural radioactivity, Rutherford for nuclear model and first nuclear disintegration, and later scientists for fission and reactors.

Final Answer:
The first clear indication that a stable nucleus can be broken down was provided by the experiments of Ernest Rutherford.