A point charge Q is placed on the x axis at origin. A second point charge, -Q, is placed at x= 5.0 m. IfQ= 70 micro Coulomb, what is the magnitude of the electrostatic force (in Nowtons) on a 80 micro Coulomb charge placed at x= 2.0 m? O none of these O 8.6 4.2 12.7 18.2