Q.Distinguish between diamagnetic, paramagnetic and ferromagnetic substances on the basis of their atomic origin, giving two examples of each and stating how each responds when placed in an external magnetic field.

Diamagnetic substances have atoms with no net moment; an applied field induces a small OPPOSING moment, so they are weakly REPELLED ($\chi$ small, negative, temperature-independent; e.g. copper, bismuth, water). Paramagnetic substances have atoms with a small permanent moment, randomly oriented until a field partially aligns them, so they are weakly ATTRACTED ($\chi$ small, positive, falls as temperature rises -- Curie's law; e.g. aluminium, oxygen). Ferromagnetic substances have permanent atomic moments that align spontaneo …