A neutral water molecule, modeled as an electric dipole with an effective charge equal to one elementary charge (\(e = 1.6 \times 10^{-19} \text{ C}\)), is placed in an electric field \(E = 2.5 \times 10^4 \text{ NC}^{-1}\). The work done to rotate it by \(180^\circ\) from its stable equilibrium position is \(5 \times 10^{-25} \text{ J}\). Find the approximate separation of the centre of charges.

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.