A paramagnetic material is kept in a magnetic field. The field is inc…

The correct answer is Option (3) → will remain constant

Each atom of a paramagnetic material has a permanent dipole moment. The random thermal motion of the atoms keeps these moments from lining up. A stronger field or a lower temperature aligns more of them. The magnetisation then rises until it reaches the saturation value, when all the dipoles are aligned with the field.

Option (1) will increase — Incorrect. Cooling raises the magnetisation only while some dipoles are not yet aligned with the field. At saturation there are none left to align.

Option (2) will decrease — Incorrect. A lower temperature means less random thermal motion, and this helps the alignment. It cannot turn the aligned dipoles away from the field.

Option (3) will remain constant — Correct. At saturation all the dipoles are perfectly aligned with the field. So the magnetisation already has its largest possible value. A further fall in temperature does not change it.

Option (4) may increase or decrease — Incorrect. A fall in temperature can only help the alignment, and the alignment is already complete. So the magnetisation neither rises nor falls.

NCERT (2026-27):
Paramagnetism – “… As the field is increased or the temperature is lowered, the magnetisation increases until it reaches the saturation value at which point all the dipoles are perfectly aligned with the field.”