Which scientist is credited with discovering the proton, the positively charged particle found in atomic nuclei?

Introduction / Context:
The proton is a fundamental particle carrying positive charge and residing in the nucleus of an atom. Understanding the existence and behaviour of protons was crucial for building accurate atomic models and for the later development of nuclear physics. This question asks you to identify the scientist who is credited with discovering the proton, a standard fact that appears in atomic structure and general science chapters.

Given Data / Assumptions:

• The particle in question is the proton, found in the atomic nucleus.
• The discoverer is a physicist who worked on atomic structure and radioactivity.
• The options include scientists linked to DNA, radioactivity and gas experiments.
• Only one of these names is widely recognised as the discoverer of the proton.

Concept / Approach:
Ernest Rutherford, a New Zealand born physicist, is credited with discovering the proton through experiments on atomic nuclei. He observed that when nitrogen and other gases were bombarded with alpha particles, positively charged hydrogen nuclei were emitted, which he identified as protons. Friedrich Miescher discovered nucleic acids, Henri Becquerel discovered radioactivity and Henry Cavendish worked on gases and the density of the Earth. None of these scientists is directly credited with discovering the proton. Therefore, Rutherford is the correct answer in this context.

Step-by-Step Solution:
Step 1: Identify the key topic as the discovery of the proton in the atomic nucleus.Step 2: Recall that Ernest Rutherford conducted scattering and nuclear experiments that led to the identification of the proton.Step 3: Locate Ernest Rutherford as option A in the list.Step 4: Recognise that Friedrich Miescher studied cell nuclei and nucleic acids, not nuclear particles like protons.Step 5: Recognise that Henri Becquerel first observed natural radioactivity but did not identify the proton.Step 6: Recognise that Henry Cavendish worked on gases and gravitation, not nuclear structure.Step 7: Select Ernest Rutherford as the discoverer of the proton.

Verification / Alternative check:
Physics and chemistry textbooks that describe the history of atomic theory always emphasise Rutherford role in proposing the nuclear model of the atom and discovering the proton. They mention his scattering experiments and nuclear reactions that identified hydrogen nuclei as positively charged building blocks of nuclei. The other scientists listed have distinct achievements in different areas. Because this pattern is very consistent across references, Rutherford is the safe and correct choice in exam situations.

Why Other Options Are Wrong:
Friedrich Miescher discovered nucleic acids, now known as DNA and RNA, which are essential biological molecules but not subatomic particles. Henri Becquerel is honoured for discovering radioactivity when he observed spontaneous emission from uranium salts. Henry Cavendish made important contributions to chemistry and physics through experiments on hydrogen and gravitation. None of these individuals discovered the proton, making options B, C and D inappropriate answers to this question.

Common Pitfalls:
Some candidates might confuse Rutherford work on the nucleus with Becquerel discovery of radioactivity and choose the wrong name. Others might guess randomly among well known scientists. To avoid such errors, remember a simple mapping: J. J. Thomson discovered the electron, Rutherford discovered the proton and James Chadwick discovered the neutron. This three part association covers the basic subatomic particles and is extremely helpful for atomic structure MCQs.

Final Answer:
The proton was discovered by Ernest Rutherford.