Consider the regular array of vertical identical current-carrying wires (with the direction of current flow as indicated in the figure alongside) protruding through a horizontal table. If we scatter some diamagnetic particles on the table,then they are likely to accumulate:

Among the following, for which substance does the magnetic susceptibility not depend on the temperature?

Assertion: The ferromagnetic substance does not obey Curie's law.
Reason: At Curie point,a ferromagnetic substance starts behaving as a paramagnetic substance.

Assertion: $A$ disc-shaped magnet is levitated above a superconducting material that has been cooled by liquid nitrogen.
Reason: Superconductors repel a magnet.

$A$ 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).

What materials should be used to make permanent magnets?