Rutherford's Experiment and Atomic Structure

Steps:

• Alpha particles were fired at thin gold foil, expecting uniform deflection based on plum pudding model.
• Most particles passed straight through undeflected, indicating atoms are mostly empty space.
• Some particles deflected at large angles, suggesting a tiny, dense, positively charged nucleus.
• Rare particles bounced straight back, confirming the nucleus's concentrated mass and charge.

Why D is correct:

• The scattering pattern directly evidenced the nuclear atom model, where a small, dense nucleus holds positive charge and most mass, as per Rutherford's 1911 interpretation.

Why the others are wrong:

• A: Nuclear fusion involves combining light nuclei into heavier ones, unrelated to scattering observations.
• B: Radioactive decay emits alpha particles but was not tested or evidenced by the scattering setup.
• C: Isotopes refer to atoms with same protons but different neutrons; the experiment focused on internal structure, not mass variants.

Final answer: D