What is the nature of the magnetic susceptibility of a diamagnetic substance?

If $\chi$ is the magnetic susceptibility and $\mu_{r}$ is the relative permeability of a ferromagnetic substance,then:

$A$ long solenoid has $1000$ turns per metre and carries a current of $1 \, A$. It has a soft iron core of $\mu_r = 1000$. The core is heated beyond the Curie temperature,$T_C$.

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

Relative permittivity and permeability of a material are $\varepsilon_r$ and $\mu_r$ respectively. Which of the following values of these quantities are allowed for a diamagnetic material?

Which of the following is desirable for making permanent magnets?