Samples of a paramagnet, a diamagnet, a superconductor and a ferromagnet are studied in a lab. Which of the following observations about such materials are correct?

• I. The susceptibility of a paramagnetic material depends on its temperature.
• II. Diamagnetic materials have a small negative susceptibility.
• III. A superconductor expels a magnetic field completely and behaves as a perfect diamagnet, with μᵣ = 0.
• IV. A ferromagnetic material remains ferromagnetic however much it is heated.