Which of the following statements are true for diamagnetic substances…

The correct answer is Option (3) → (A) and (D) only

In a diamagnetic substance an applied field induces a weak magnetisation opposite to the field. So the substance moves from stronger to weaker field regions, and its susceptibility is small and negative (\( -1 \le \chi \lt 0 \)).

(A) They are feebly repelled by magnet — Correct. The induced magnetisation opposes the field, so a magnet pushes them away weakly.

(B) They are feebly attracted by magnet — Incorrect. Feeble attraction is the behaviour of paramagnetic substances.

(C) Susceptibility is small and positive — Incorrect. A small positive susceptibility again describes a paramagnetic substance.

(D) Susceptibility is small and negative — Correct. The magnetisation is opposite to the field, so \( \chi = M/H \) is negative and small.

NCERT (2026-27):
Magnetisation and Magnetic Intensity – “… χ is small and positive for materials, which are called paramagnetic. It is small and negative for materials, which are termed diamagnetic. In the latter case M and H are opposite in direction.”

Diamagnetism – “… Diamagnetic substances are those which have tendency to move from stronger to the weaker part of the external magnetic field. In other words, unlike the way a magnet attracts metals like iron, it would repel a diamagnetic substance.”