Question

describe a simple experiment to show that the total charge on a pair of objects that have been rubbed together is zero

Answer 1

HERE IZ A ANSWER.......HOPE IT WILL HELP
WHEN WE TAKE TWO OBJECTS......A glass rod and a silkmoth , a glass rod is rubbed against a silk cloth, then glass object shows +ve charge and silk cloth acquired -ve charge.
The amount of charge acquired by both the object must be equal, so that the net charge of the system is zero.
This is so because, according to the law of conservation of charges, charge can neither be created nor can it be destroyed

Answer 2

This Will help you when a glass rod is taken near a silk cloth and rubbed together the glass rod attack like a magnet