Answer:
According to conservation of electric charge ,the total charge on an isolated system remains constant.
( By isolated system we mean the system in which there is no external disturbance i.e.,there is no charged or uncharged conductor in the neighbourhood and hence no leakage of charge).
Here is the example of conservation of electric charge in radioactive decay.
92U238 (Parent atom) ------->(decays) 90U234(daughter atom) + 2He4(alpha particle)
The amount of charge present before decay is 92e and this is equal to the amount of charge after the decay ( 90e + 2e = 92e).Hence electric charge is conserved.