(N/A) When a glass rod is rubbed with a silk cloth,electrons are transferred from the glass rod to the silk cloth.
As a result,the glass rod acquires a positive charge and the silk cloth acquires an equal amount of negative charge.
The total charge of the system (glass rod + silk cloth) before rubbing is zero,and after rubbing,the total charge remains zero because the net charge is the algebraic sum of the positive and negative charges $(+q + (-q) = 0)$.
This observation is consistent with the law of conservation of charge,which states that the total electric charge of an isolated system remains constant over time.
Charges are neither created nor destroyed,only transferred from one body to another.