how does electric force between them change:A:distance between them is tripled:B:charge of 1 object is tripled

Answer 1

The force goes directly with charge and 1 divided by the distance squared. It should be obvious.

Answer 2

The equation of electric force is like this:
F1 = k (q1)(q2) / r^2
A. the new r is equal to 3r then F2 = k (q1)(q2) / (3r)^2. Then F2 = 1/9F1. The force will be 1/9 less.
b. F3 = k (q1)(3q2) / r^2 = 3k (q1)(q2) / r^2. F3 = 3 F1. The force is tripled.

Answer 3

F=KQq/R^2

A: force will be reduced to (1/9)th of original force

B:force will increase to 3 times of given force