If three uncharged styrofoam balls are placed together and agitated so that one gains 3 cc of charge and another gains 4 cc of charge, how much charge must there be on the third one

-7 C

Explanation:

Assuming that object other than the styrofoam balls was part of the charge transfer. In order to maintain charge balance, the initial charge of the system must equal the ending charge. If all balls were uncharged initially, the ending charge on the third ball must be:

There must be -7 C of charge on the third ball.

12000j is work done