When a ferromagnetic substance is placed in a magnetic field, it becomes a permanent magnet because:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → all the domains get oriented in the direction of the magnetic field
In a ferromagnetic solid (Fe, Co, Ni, \( \ce{CrO2} \)) the metal ions are grouped into small regions called domains; each domain behaves like a tiny magnet. In an unmagnetised piece the domains point randomly and their moments cancel. In a magnetic field all the domains line up in the direction of the field, giving a strong magnetic effect, and this ordering remains even after the field is removed, so the substance becomes a permanent magnet.
Why the other options are incorrect
Option (2) opposite to the field — Incorrect. Domains aligned against the field would oppose it; that does not happen in a ferromagnetic substance.
Option (3) domains get oriented randomly — Incorrect. Random orientation is the unmagnetised state, in which the moments cancel.
Option (4) domains are not affected — Incorrect. The domains are strongly affected; their alignment is what produces the magnetism.
Note: This question is from the pre-rationalised NCERT book (2022-23). The topic is not there in the latest NCERT book (2026-27), and it is also out of the CUET 2026 syllabus.
NCERT (Pre-rationalised edition, 2022-23):
Ferromagnetism – “… In an unmagnetised piece of a ferromagnetic substance the domains are randomly oriented and their magnetic moments get cancelled. When the substance is placed in a magnetic field all the domains get oriented in the direction of the magnetic field and a strong magnetic effect is produced. This ordering of domains persist even when the magnetic field is removed and the ferromagnetic substance becomes a permanent magnet.”