Which of the following is the correct statement?

A. Paragmatic 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:

A, B and C only

The correct answer is Option (1) → A, B and C only.

Let us go through each statement in detail and explain why it is correct or incorrect:

A. Paramagnetic substances lose their magnetism in the absence of a magnetic field.

Paramagnetic substances have unpaired electrons, which give rise to a net magnetic moment. However, the magnetic moments are randomly oriented in the absence of an external magnetic field.

When an external magnetic field is applied, these magnetic moments align with the field, causing the material to become magnetized. Once the magnetic field is removed, the thermal motion causes the magnetic moments to lose alignment, and the substance no longer exhibits magnetism.

This statement is correct because paramagnetic materials lose their magnetism when the external magnetic field is absent.

B. Ferromagnetic substances are attracted very strongly by a magnetic field.

Ferromagnetic substances (such as iron, cobalt, and nickel) have a high degree of magnetic ordering. They contain regions called magnetic domains, where the magnetic moments of atoms are aligned in the same direction.

In the presence of an external magnetic field, these domains align strongly with the field, causing the substance to exhibit strong magnetism. Even after the magnetic field is removed, the domains may remain aligned, which is why ferromagnetic materials can retain their magnetism (this property is known as **hysteresis**).

This statement is correct because ferromagnetic substances are strongly attracted by a magnetic field.

C. Fe₃O₄ loses ferrimagnetism on heating.

Fe₃O₄ (magnetite) is a ferrimagnetic material. Ferrimagnetism occurs when the magnetic moments of ions in different sublattices are aligned in opposite directions, but the magnitudes of the magnetic moments are unequal, resulting in a net magnetic moment.

When ferrimagnetic materials are heated above a critical temperature known as the Curie temperature, the thermal energy disrupts the alignment of magnetic moments, and the material loses its magnetic properties.

This statement is correct because Fe₃O₄ loses ferrimagnetism when heated above its Curie temperature.

D. Diamagnetic substances are strongly attracted by a magnetic field.

Diamagnetic substances have no unpaired electrons, and their magnetic moments cancel out. In the presence of an external magnetic field, diamagnetic materials create a weak induced magnetic field in the opposite direction, which causes them to be weakly repelled by the magnetic field.

Examples of diamagnetic materials include bismuth and copper.

This statement is incorrect because diamagnetic substances are not attracted but weakly repelled by magnetic fields.

E. Paramagnetic substances are magnetized in a magnetic field in different directions.

Paramagnetic substances are magnetized in the same direction as the applied magnetic field because their unpaired electrons align with the external magnetic field.

Once the external magnetic field is removed, the alignment is lost due to thermal motion, and the material no longer exhibits magnetism.

This statement is incorrect because paramagnetic substances are magnetized in the same direction as the magnetic field, not in different directions.

Thus, the correct answer is A, B, and C only.