When a positive charge (+ q) is brought near one face of a metal cube…

The correct answer is Option (4) → face near the charge (+ q) becomes negatively charged, and the opposite face becomes positively charged

This is electrostatic induction. The free electrons of the metal are attracted by the positive charge and gather on the near face, leaving an equal positive charge on the opposite face. No charge enters or leaves the cube, so by conservation of charge it stays neutral overall.

Option (1) cube becomes negatively charged — Incorrect. No charge is transferred to the cube, so its net charge stays zero.

Option (2) cube becomes positively charged — Incorrect. The net charge stays zero for the same reason.

Option (3) face near the charge (+ q) becomes positively charged, and the opposite face becomes negatively charged — Incorrect. The signs are reversed: electrons are pulled towards \( +q \), so the near face is negative.

Option (4) face near the charge (+ q) becomes negatively charged, and the opposite face becomes positively charged — Correct. The electrons gather on the near face and the far face is left positive.

Note: This question is from the pre-rationalised NCERT book (2022-23). The topic was removed from the latest NCERT book (2026-27), and it also appears to be out of the CUET 2026 syllabus.

NCERT (Pre-rationalised edition, 2022-23):
Charging by Induction – “… (ii) Bring a positively charged rod near one of the spheres, say A, taking care that it does not touch the sphere. The free electrons in the spheres are attracted towards the rod. This leaves an excess of positive charge on the rear surface of sphere B. … The left surface of sphere A, has an excess of negative charge and the right surface of sphere B, has an excess of positive charge.”