Which of the following is the correct statement?
A. Paramagnetic substances lose their magnetism in the absence of magnetic field.
B. Ferromagnetic substances are attracted very strongly by a magnetic field.
C. \(Fe_3O_4\) lose ferrimagnetism on heating.
D. Diamagnetic substances are strongly attracted by a magnetic field.
E. Paramagnetic substances are magnetized in a magnetic field in different directions
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → A, B and C only
Substances are classed by their behaviour in a magnetic field, which depends on unpaired electrons and on how their magnetic moments line up.
A. Paramagnetic substances lose their magnetism in the absence of magnetic field. — True. Their unpaired electrons are aligned only while the field acts.
B. Ferromagnetic substances are attracted very strongly by a magnetic field. — True. Fe, Co, Ni, Gd and \( \ce{CrO2} \) are strongly attracted and can be permanently magnetised.
C. Fe3O4 loses ferrimagnetism on heating. — True. Magnetite is ferrimagnetic, and ferrimagnetic substances lose ferrimagnetism on heating and become paramagnetic.
D. Diamagnetic substances are strongly attracted by a magnetic field. — False. Diamagnetic substances (\( \ce{H2O} \), NaCl, \( \ce{C6H6} \)) are weakly repelled; all their electrons are paired.
E. Paramagnetic substances are magnetized in a magnetic field in different directions. — False. They are magnetised in the same direction as the field; diamagnetic substances are magnetised in the opposite direction.
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):
Paramagnetism – “Paramagnetic substances are weakly attracted by a magnetic field. They are magnetised in a magnetic field in the same direction. They lose their magnetism in the absence of magnetic field. Paramagnetism is due to presence of one or more unpaired electrons which are attracted by the magnetic field. O2, Cu2+, Fe3+, Cr3+ are some examples of such substances.”
Diamagnetism – “Diamagnetic substances are weakly repelled by a magnetic field. H2O, NaCl and C6H6 are some examples of such substances. They are weakly magnetised in a magnetic field in opposite direction. Diamagnetism is shown by those substances in which all the electrons are paired and there are no unpaired electrons. Pairing of electrons cancels their magnetic moments and they lose their magnetic character.”
Ferromagnetism – “A few substances like iron, cobalt, nickel, gadolinium and CrO2 are attracted very strongly by a magnetic field. Such substances are called ferromagnetic substances. Besides strong attractions, these substances can be permanently magnetised.”
Ferrimagnetism – “Ferrimagnetism is observed when the magnetic moments of the domains in the substance are aligned in parallel and anti-parallel directions in unequal numbers (Fig. 1.32 c). They are weakly attracted by magnetic field as compared to ferromagnetic substances. Fe3O4 (magnetite) and ferrites like MgFe2O4 and ZnFe2O4 are examples of such substances. These substances also lose ferrimagnetism on heating and become paramagnetic.”