The magnetic susceptibility $\chi$ for superconductors is . . . . . . .

Nickel shows ferromagnetic property at room temperature. If the temperature is increased beyond Curie temperature,then it will show

$A$ superconductor exhibits perfect

$A$ sample of paramagnetic salt contains $2.0 \times 10^{24}$ atomic dipoles each of dipole moment $1.5 \times 10^{-23} \; J \, T^{-1}$. The sample is placed under a homogeneous magnetic field of $0.64 \; T$ and cooled to a temperature of $4.2 \; K$. The degree of magnetic saturation achieved is $15 \%$. What is the total dipole moment of the sample for a magnetic field of $0.98 \; T$ and a temperature of $2.8 \; K$? (Assume Curie's law)

For protecting a sensitive equipment from the external magnetic field,it should be

The curve representing the relationship between the magnetic moment $(M)$ and the temperature $(T)$ of a ferromagnetic material is: