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

Which of the following is desirable for making permanent magnets?

The magnetic susceptibility is negative for

What type of materials can be used to make an electromagnet?

There are four light-weight rod samples $A, B, C, D$ separately suspended by threads. $A$ bar magnet is slowly brought near each sample and the following observations are noted:
$(i)$ $A$ is feebly repelled
$(ii)$ $B$ is feebly attracted
$(iii)$ $C$ is strongly attracted
$(iv)$ $D$ remains unaffected
Which one of the following is true?

If the magnetic dipole moment of an atom of diamagnetic material,paramagnetic material,and ferromagnetic material are denoted by $\mu_d, \mu_p, \mu_f$ respectively,then: