Which observation from Rutherford's gold foil experiment was inconsistent with the plum pudding model of the atom?

• A. All alpha particles were absorbed by the gold foil.
• B. Most alpha particles passed straight through the foil with little or no deflection.
• C. A small fraction of alpha particles were deflected at large angles, with some even bouncing back.
• D. Alpha particles caused the gold foil to emit visible light.

Answer: (C)

Verified step by step guidance

1. Recall the plum pudding model of the atom, which proposed that atoms consist of a diffuse cloud of positive charge with negatively charged electrons embedded throughout, implying that alpha particles should pass through with minimal deflection.
2. Understand that Rutherford's gold foil experiment involved firing alpha particles at a thin sheet of gold foil and observing their scattering patterns.
3. Note that if the plum pudding model were correct, alpha particles would mostly pass through the foil with little or no deflection, as the positive charge was thought to be spread out evenly.
4. Identify the key observation from Rutherford's experiment: a small fraction of alpha particles were deflected at large angles, with some even bouncing back, indicating the presence of a small, dense, positively charged nucleus.
5. Conclude that this observation was inconsistent with the plum pudding model because it suggested that positive charge is concentrated in a tiny nucleus rather than spread diffusely, leading to significant deflections of some alpha particles.