$A$ magnetic needle suspended by a silk thread is vibrating in the earth's magnetic field. If the temperature of the needle is increased by $500^{\circ}C$,then

What are soft ferromagnetic materials? Write the uses of soft ferromagnetic materials.

The variation of magnetic susceptibility $(\chi)$ with temperature $(T)$ for a diamagnetic substance is shown correctly by which graph?

The relative permeability is represented by $\mu_r$ and the susceptibility is denoted by $\chi$ for a magnetic substance. Then for a paramagnetic substance:

Statement $I :$ The ferromagnetic property depends on temperature. At high temperature,a ferromagnet becomes a paramagnet.
Statement $II :$ At high temperature,the domain wall area of a ferromagnetic substance increases.
In the light of the above statements,choose the most appropriate answer from the options given below :

The relation $H \propto I$ and the susceptibility $\chi = \frac{I}{H}$ are not applicable for which of the following substances?