Rutherford's Alpha-Particle Scattering Experiment

Steps:

• Alpha particles were fired at a thin gold foil.
• Most particles passed straight through, indicating atoms are mostly empty space.
• Some particles deflected at large angles, showing a concentrated positive charge in the atom.
• This pattern disproved the plum pudding model and supported a nuclear structure.

Why D is correct:

• The large-angle deflections indicated a tiny, dense nucleus with positive charge, as per Rutherford's nuclear atom model where electrons orbit this core.

Why the others are wrong:

• A: The experiment involved scattering, not fusing atomic nuclei.
• B: It used alpha particles from decay but focused on atomic structure, not decay processes.
• C: Isotopes involve varying neutron numbers in nuclei, unrelated to the scattering observations.

Final answer: D