Which one of the following is a non-magnetic substance?

$A$ ferromagnetic material is heated above its $Curie$ temperature. Which one is a correct statement?

$A$ 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).

For two types of magnetic materials $A$ and $B$, the variation of $\frac{1}{\chi}$ ($\chi$: magnetic susceptibility) versus temperature $T$ is shown in the figure. Then:

What is a hard ferromagnetic substance?

The magnetic susceptibility of a paramagnetic substance is: