Ferromagnetic materials have . . . . . . permeability and . . . . . . retentivity.

The materials having negative magnetic susceptibility are

Curie temperature is the temperature above which

The variation of magnetic susceptibility $(\chi)$ with magnetising field $(H)$ for a paramagnetic substance is represented by which of the following graphs?

Explain quantitatively the order of magnitude difference between the diamagnetic susceptibility of ${N_2} \left( { \sim 5 \times {{10}^{ - 9}}} \right)$ (at $STP$) and ${Cu} \left( { \sim {{10}^{ - 5}}} \right)$.

Assertion $(A)$: Electromagnets are made of soft iron.
Reason $(R)$: Coercivity is small for soft iron.