Which of the following statements about Rutherford’s alpha-particle scattering experiment with a thin metal foil are correct?
(A) Most of the alpha particles passed straight through the foil.
(B) Some of the alpha particles were deflected by small angles.
(C) A very small number of alpha particles (about one in 12,000) bounced back.
(D) From the results, Rutherford concluded that the positive charge is spread evenly over the whole atom.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → (A), (B) and (C) only
Fast-moving alpha particles (positively charged) were fired at a very thin metal foil, and their paths were observed.
(A) Most of the alpha particles passed straight through the foil. — Correct. This showed that most of the space inside the atom is empty.
(B) Some of the alpha particles were deflected by small angles. — Correct. They passed close to a region of positive charge and were pushed aside.
(C) A very small number of alpha particles (about one in 12,000) bounced back. — Correct. Only a head-on approach to a tiny, heavy, positive centre could turn them back.
(D) From the results, Rutherford concluded that the positive charge is spread evenly over the whole atom. — Incorrect. He concluded the opposite: all the positive charge and nearly all the mass are packed in a very small nucleus at the centre.