Alnico is an alloy of . . . . . . .

Magnetic susceptibility for a paramagnetic and diamagnetic material is respectively

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?

Given below are two statements; one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A:$ Electromagnets are made of soft iron.
Reason $R:$ Soft iron has high permeability and low retentivity.
In the light of the above statements,choose the most appropriate answer from the options given below.

The most exotic diamagnetic materials are

What is a hard ferromagnetic substance?