A few substances are attracted very strongly by magnetic field. They can be permanently magnetized. Their domains get oriented in the direction of the magnetic field even after magnetic field is removed. This
substance is :

Ferromagnetic

The correct answer is option 2. Ferromagnetic.

Ferromagnetic materials are a class of materials that exhibit strong magnetic properties. These materials can be permanently magnetized and show strong attraction to external magnetic fields. The key to their behavior lies in the alignment of magnetic domains within the material.

Magnetic Domains:

Magnetic domains are regions within a material where the magnetic moments of atoms (spins of electrons) are aligned in the same direction.

In ferromagnetic materials, these domains are initially randomly oriented, which cancels out the overall magnetization.

When a magnetic field is applied, the magnetic moments within the domains align in the direction of the magnetic field, leading to a strong magnetic effect.

Key Properties of Ferromagnetic Materials:

Strong Attraction to Magnetic Field:

Ferromagnetic materials are strongly attracted to external magnetic fields because the individual atomic magnetic moments align in the direction of the field.

Permanent Magnetization:

After the external magnetic field is removed, ferromagnetic materials retain their magnetization because the alignment of the domains persists.

This is the key property of ferromagnetic materials — they can be permanently magnetized and act as magnets even when there is no external magnetic field.

Curie Temperature:

Ferromagnetic materials lose their ferromagnetism above a certain temperature, known as the Curie temperature. Above this temperature, the thermal energy disrupts the alignment of magnetic moments, and the material behaves like a paramagnet, meaning the material no longer retains its magnetization after the magnetic field is removed.

Examples of Ferromagnetic Materials:

Iron (Fe): One of the most common ferromagnetic materials.

Nickel (Ni) and Cobalt (Co): These metals also exhibit strong ferromagnetic behavior.

Certain alloys, like alnico (an alloy of aluminum, nickel, cobalt, and iron), are ferromagnetic.

How Ferromagnetism Works:

Before a Magnetic Field is Applied:

The magnetic domains in a ferromagnetic material are randomly oriented, so the material shows no net magnetization.

When a Magnetic Field is Applied:

The magnetic moments in different domains start to align with the field. As more domains align, the material becomes magnetized, showing strong attraction to the external magnetic field.

After the Magnetic Field is Removed:

Even after the external magnetic field is removed, the domains remain aligned, causing the material to remain magnetized. This property allows ferromagnetic materials to become permanent magnets.

Comparison with Other Magnetic Behaviors:

Paramagnetic Materials:

In paramagnetic materials, individual magnetic moments align with an external magnetic field, but the alignment is weak, and they lose their magnetization once the field is removed. The magnetic domains do not stay aligned, so paramagnetic substances are only weakly attracted to a magnetic field.

Antiferromagnetic Materials:

In antiferromagnetic materials, the magnetic moments of atoms align in opposite directions, resulting in no net magnetization. The opposing spins cancel each other out. These materials do not exhibit strong magnetic attraction and cannot be permanently magnetized.

Ferrimagnetic Materials:

In ferrimagnetic materials, the magnetic moments align in opposite directions like in antiferromagnetism, but the opposing moments are not equal in strength, so there is some net magnetization. These materials are magnetically weaker than ferromagnetic materials but can still retain some magnetization after the external field is removed.

Conclusion:
Ferromagnetic materials have unique properties due to their strong magnetic domains that align in the direction of an external magnetic field. Once the field is removed, these domains remain aligned, leading to permanent magnetization. This ability to be strongly attracted to a magnetic field and retain magnetization distinguishes ferromagnetic materials from other types of magnetic substances like paramagnetic, antiferromagnetic, or ferrimagnetic materials.

Thus, the correct answer is 2. Ferromagnetic.