Which force provides the centripetal force to the electron revolving…

The correct answer is Option (4) → Attractive electrostatic force

Option (1) Gravitational force — Incorrect. The gravitational attraction between an electron and a proton is about \( 10^{39} \) times weaker than the electric attraction between them. It is far too weak to hold the electron in its orbit.

Option (2) Nuclear force — Incorrect. The nuclear force acts between nucleons and falls to zero beyond a few femtometres. The electron is not a nucleon, and it orbits about \( 10^{-10}\,\mathrm{m} \) from the nucleus.

Option (3) Repulsive electrostatic force — Incorrect. The electron is negative and the nucleus positive, and unlike charges attract. A repulsive force would point away from the centre and could not act as a centripetal force.

Option (4) Attractive electrostatic force — Correct. The electrostatic attraction between the negative electron and the positive nucleus is directed towards the nucleus. It provides the centripetal force for the circular orbit, \( F_e=F_c \).

NCERT (2026-27):
Electron Orbits – “The Rutherford nuclear model of the atom which involves classical concepts, pictures the atom as an electrically neutral sphere consisting of a very small, massive and positively charged nucleus at the centre surrounded by the revolving electrons in their respective dynamically stable orbits. The electrostatic force of attraction, F_e between the revolving electrons and the nucleus provides the requisite centripetal force (F_c) to keep them in their orbits.”