The magnetic moment of a diamagnetic atom is

Which of the following is most suitable for the core of electromagnets?

Which of the following is the most suitable material for making a permanent magnet?

$A$ small rod of bismuth is suspended freely between the poles of a strong electromagnet. It is found to arrange itself at right angles to the magnetic field. This observation establishes that bismuth is

The magnetic susceptibility of a paramagnetic material at $-73^{\circ} C$ is $0.0075$. Its value at $-173^{\circ} C$ will be

The materials having negative magnetic susceptibility are