Identify the correct statement among the options given below.

The correct answer is Option (3) → Electrostatic force is a conservative force.

The deciding ideas are that the electrostatic force is conservative and that charge is conserved and quantised.

Option (1) The potential energy of a system of charges depends on the way the present state of its configuration is achieved. — Incorrect. Because the electrostatic force is conservative, the potential energy depends only on the final configuration, not on the way it was reached.

Option (2) A free proton can decay into a neutron and one electron — Incorrect. Charge would not be conserved: +e cannot become 0 + (−e). A free proton is also stable, being lighter than a neutron.

Option (3) Electrostatic force is a conservative force. — Correct. The work done by the electrostatic force depends only on the initial and final positions, and the work around any closed path is zero.

Option (4) In the equation, q = n.e for an amount of charge q, e is the quantum of charge on a proton, n may have values of 1, 5, 1.5, 1.9. — Incorrect. By quantisation of charge, n must be an integer; 1.5 and 1.9 are not allowed.

NCERT (2026-27):
Summary – “… Electrostatic force is a conservative force. Work done by an external force (equal and opposite to the electrostatic force) in bringing a charge \( q \) from a point \( R \) to a point \( P \) is \( q(V_P - V_R) \), which is the difference in potential energy of charge \( q \) between the final and initial points.”