Which of the following observations from Rutherford's gold foil experiment provided direct evidence for the e… - RRB Nsg Superintendent -29 April 2025 (Shift-1st)

RRB Nsg Superintendent -29 April 2025 (Shift-1st)

General Knowledge

Easy

Appeared in: RRB Nsg Superintendent -29 April 2025 (Shift-1st)

Explanation

In Rutherford's experiment, the most surprising observation was that a tiny fraction of alpha particles (about 1 in 20,000) were deflected at large angles, with some even bouncing straight back (180° deflection).
Alpha particles are positively charged and relatively heavy.
For a heavy alpha particle to be repelled so strongly that it reverses its direction, it must have collided with a region of highly concentrated positive charge and immense mass.
This led to the revolutionary conclusion that the atom's positive charge and nearly all its mass are concentrated in a very small, dense center: the nucleus.

Option B: This observation was also crucial, but it led to the conclusion that an atom is mostly empty space, not that it contains a dense nucleus.
Option C: This statement is factually incorrect and contradicts the findings of the experiment, which showed the mass is concentrated in the central nucleus.
Option D: The idea of electrons orbiting the nucleus was part of the planetary model that Rutherford proposed to explain the experimental results. It was a theoretical inference, not a direct observation from the scattering of alpha particles.

Visual 1: Diagram: Rutherford's gold foil experiment. This visual shows the setup with the alpha particle source, the thin gold foil, and the circular detector screen. It illustrates the paths of the alpha particles: most passing straight through, some deflecting slightly, and a few bouncing back, helping to visualize the key observations.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Rutherford's Atomic Model as background academic context rather than a clinical decision trigger.
The principles of how charged particles interact with dense matter are fundamental to radiation therapy in oncology. High-energy beams are used to target and destroy dense tumor cells, a concept rooted in the same physics as alpha particles interacting with the nucleus.
Understanding atomic structure is crucial for interpreting medical imaging techniques like Positron Emission Tomography (PET) scans, which use radioactive isotopes that decay and emit particles (positrons) that interact with electrons in tissue.
What if? If most alpha particles had been deflected instead of passing through, it would have supported the earlier 'plum pudding' model where positive charge is spread out. In that case, our understanding of radiation's interaction with tissue for therapy and imaging would be completely different, likely focusing on uniform absorption rather than targeted particle collisions.

How to Approach the Question

First, identify the core concept of the question, which is Rutherford's gold foil experiment and its conclusions about atomic structure.
Note the specific keywords in the question: 'direct evidence' for a 'dense atomic nucleus'. This means you are looking for the specific observation that proves the nucleus is small and massive.
Analyze each option by recalling the three main observations from the experiment and what each one proved.
Observation 1: Most particles passed straight through. Conclusion: The atom is mostly empty space.
Observation 2: Some particles were slightly deflected. Conclusion: The atom has a positively charged center.
Observation 3: A very few particles bounced back. Conclusion: The atom's positive charge and mass are concentrated in a tiny, dense nucleus.

Concept Tested & Keywords

Concept Tested: Rutherford's Atomic Model
Stem keywords: Rutherford's gold foil experiment, direct evidence, dense atomic nucleus
Lead-in keywords: Which of the following

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