Which of the following is NOT correct according to Rutherford’s model…

The correct answer is Option (4) → The model established the stability of the atom.

In Rutherford’s nuclear model, the entire positive charge and most of the mass of the atom sit in a tiny nucleus at the centre. The electrons move in orbits around it, like planets around the sun.

Option (1) Most of the space inside an atom is empty. — Correct according to Rutherford’s model. The atom (about \( 10^{-10}\,\mathrm{m} \)) is 10,000 to 100,000 times larger than the nucleus. So most of an atom is empty space. This is why most α-particles go straight through a thin foil.

Option (2) The electrons revolve around the nucleus under the influence of the Coulomb force acting on them. — Correct according to Rutherford’s model. The electrostatic attraction between the nucleus and each electron provides the centripetal force that keeps the electron in its orbit.

Option (3) Most of the mass of the atom and its positive charge are concentrated at the centre. — Correct according to Rutherford’s model. Only such a small, dense, positive nucleus can repel an α-particle strongly enough to turn it back, as seen for about 1 in 8000 α-particles.

Option (4) The model established the stability of the atom. — Not correct according to Rutherford’s model. A revolving electron is always accelerated, and by classical electromagnetic theory it should radiate energy continuously, spiral inward and fall into the nucleus. So the model could not explain why atoms are stable.

NCERT (2026-27):
Bohr Model of the Hydrogen Atom – “… We know that an object which moves in a circle is being constantly accelerated – the acceleration being centripetal in nature. According to classical electromagnetic theory, an accelerating charged particle emits radiation in the form of electromagnetic waves. The energy of an accelerating electron should therefore, continuously decrease. The electron would spiral inward and eventually fall into the nucleus …. Thus, such an atom can not be stable.”