In Rutherford's gold foil experiment, what caused the deflection of the alpha particles?

• A. The positively charged nucleus of the gold atoms
• B. The vacuum in the experimental chamber
• C. The gold foil's surface impurities
• D. The electrons surrounding the gold atoms

Answer: (A)

Verified step by step guidance

1. Recall the setup of Rutherford's gold foil experiment, where alpha particles (which are positively charged) were directed at a thin sheet of gold foil.
2. Understand that most alpha particles passed through the foil with little or no deflection, but some were deflected at large angles.
3. Recognize that the deflection occurs due to electrostatic forces between the positively charged alpha particles and something within the gold atoms.
4. Identify that the gold atoms have a small, dense, positively charged nucleus, which repels the positively charged alpha particles, causing their deflection.
5. Conclude that the deflection of alpha particles is caused by the positively charged nucleus of the gold atoms, not by vacuum, surface impurities, or electrons.