In the context of Rutherford’s \(\alpha\)-scattering experiment and Rutherford’s nuclear model of atom, identify the incorrect statement among the following.
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → When an \(\alpha\)-particle comes near a nucleus, the intense electric field there scatters it through a small angle.
In Rutherford’s experiment a few α-particles are deflected through large angles. Only a tiny, massive, positively charged nucleus can repel them so strongly.
Option (1) The scattering of \(\alpha\)-particles is solely due to electrostatic repulsion between \(\alpha\)-particles and positive charges in the target atom. — Correct. Coulomb repulsion by the nucleus; electrons are too light to deflect an α-particle.
Option (2) The entire positive charge and most of the mass of the atom are concentrated in the nucleus. — Correct. The central idea of the nuclear model.
Option (3) The electrons move in orbits about the nucleus just as the planets do around the sun. — Correct. Rutherford’s planetary model.
Option (4) When an \(\alpha\)-particle comes near a nucleus, the intense electric field there scatters it through a small angle. — Incorrect. It scatters the α-particle through a large angle.
NCERT (2026-27):
Alpha-Particle Scattering and Rutherford’s Nuclear Model of Atom – “… Rutherford argued that, to deflect the \( \alpha \)-particle backwards, it must experience a large repulsive force. … In Rutherford’s nuclear model of the atom, the entire positive charge and most of the mass of the atom are concentrated in the nucleus with the electrons some distance away. The electrons would be moving in orbits about the nucleus just as the planets do around the sun. … However, when \( \alpha \)-particle happens to come near a nucleus, the intense electric field there scatters it through a large angle.”