posted by Sonam .
A charge of 3.75 10-9 C is located 3.1 m from a charge of -3.10 10-9 C. Find the magnitude of the electrostatic force exerted by one charge on the other.
c)remains the same
You have not said if the separation of the charges is changing. The choices offered do not answer the question.
I believe you copied the problem's choices incorrectly.
In any case, use Coulomb's to determine the magnitude of the electrostatic force