(a) When a glass rod is rubbed with a silk cloth, it acquires positive charge. When it is touched with the metal top of an electroscope, both the metal top and leaves acquires a positive charge due to conduction. As a result of the positive charge on both the leaves, the divergence of leaves takes place.

(b) After rubbing the plastic comb, it acquires negative charge. When it is touched with the metal cap of an electroscope, both the metal cap and the leaves acquire negative charge due to conduction. As a result of negative charge on both the leaves, divergence of leaves takes place.