Assertion: Ferromagnetic substances become paramagnetic above the Curie temperature.
Reason: Domains are destroyed at high temperature.

The permanent magnet is made from which one of the following substances?

Which of the following statements is true in respect of diamagnetic substances?

Which of the following is desirable for making permanent magnets?

$A$ sample of paramagnetic salt contains $20 \times 10^{24}$ atomic dipoles each of dipole moment $1.5 \times 10^{-23} \ J \ T^{-1}$. The sample is placed under a homogeneous magnetic field of $0.84 \ T$,and cooled to a temperature of $4.2 \ K$. The degree of magnetic saturation achieved is equal to $15 \%$. What is the total dipole moment (approximate) of the sample for a magnetic field of $0.98 \ T$ and a temperature of $2.8 \ K$? (Assume Curie's law).

Given below are two statements: one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R)$. Consider a ferromagnetic material:
Assertion $(A)$: The individual atoms in a ferromagnetic material possess a magnetic dipole moment and interact with one another in such a way that they spontaneously align themselves forming domains.
Reason $(R)$: At high enough temperature, the domain structure of a ferromagnetic material disintegrates. Thus, magnetization will disappear at a high enough temperature known as the Curie temperature.
In the light of the above statements, choose the correct answer from the options given below: