Final answer:
The electrostatic force between two charged particles becomes quartered if the distance between them is doubled, according to Coulomb's Law.
Step-by-step explanation:
When two very small charged particles exert an electrostatic force F on each other, and the distance between them is doubled, according to Coulomb's Law, the force between them becomes inversely proportional to the square of the distance. Therefore, if the distance is doubled, the force is not simply halved or doubled, but rather the square of the distance factor comes into play. Specifically, the new force would be the original force divided by the square of 2 (which is 4), so the force would be quartered, or become ⅔ of the original force.