Asystem of two charges has a potential energy of -5 joules. which of the following is a possible potential energy for the system after it has been permitted to accelerate for a few seconds?

There are no listed choices.

If we release those two charges from rest, the electric field created by the charges will accelerate them in the direction of decreasing electric potential energy, bringing the electric potential energy of the system to some value less than -5J.

force required to detach it is given by

charges are taken to be fundamental charge

now we have

so above is the minimum distance at which it will detach