Name two elements, one having positive susceptibility and the other having negative susceptibility. What does negative susceptibility signify?     

It is the ratio of intensity of magnetisation (I) produced in the material to the intensity of magnetising field (H)

${\mathrm{\chi }}_{\mathrm{m}}=\frac{\mathrm{I}}{\mathrm{H}}$

Positive susceptibility: para-magnetic material

Example: Al, Ca.

Negative susceptibility: diamagnetic material

Example: Bi, Cu.

Negative susceptibility signifies that the material is diamagnetic in nature.