Match the LIST-I with LIST-II (In the context of Rutherford's scattering experiment involving alpha particles and the Gold nucleus).
| LIST-I | LIST-II |
| A. For head-on collision, the scattering angle is______ | I. 1° |
| B. For large impact parameters, the scattering angle is ______. | II. ~ 180° |
| C. Only about 0.14% of the incident alpha particles scatter by more than______. | III. 90° |
| D. About 1 in 8000 incident alpha particles deflect by more than ______. | IV. ~0° |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → A - II, B - IV, C - I, D - III
In Rutherford’s experiment the deflection of an alpha particle depends on its impact parameter b, the perpendicular distance of its initial line of motion from the nucleus: the smaller b is, the larger the scattering angle.
(A) For head-on collision, the scattering angle is______ — this matches (II) ~ 180°. With b = 0 the particle is stopped by the repulsion and turns straight back.
(B) For large impact parameters, the scattering angle is ______. — this matches (IV) ~0°. A particle passing far from the nucleus feels only a weak repulsion and goes on almost undeviated.
(C) Only about 0.14% of the incident alpha particles scatter by more than______. — this matches (I) 1°. Most of the gold atom is empty space, so most alpha particles pass with little or no deflection.
(D) About 1 in 8000 incident alpha particles deflect by more than ______. — this matches (III) 90°. Only the few particles that come very close to the tiny, massive nucleus are turned back by more than 90°.
NCERT (2026-27):
Alpha-Particle Scattering and Rutherford’s Nuclear Model of Atom – “… Many of the α-particles pass through the foil. It means that they do not suffer any collisions. Only about 0.14% of the incident α-particles scatter by more than 1°; and about 1 in 8000 deflect by more than 90°.”
Alpha-Particle Trajectory – “… It is seen that an α-particle close to the nucleus (small impact parameter) suffers large scattering. In case of head-on collision, the impact parameter is minimum and the α-particle rebounds back (\( \theta \cong \pi \)). For a large impact parameter, the α-particle goes nearly undeviated and has a small deflection (\( \theta \cong 0 \)).”