6. (a) Calculate the attractive force between a pair of K+ and Cl- ions that just touch each other. Assume the ionic radius of the K+ ion to be 0.133nm and that of the Cl- ion to be 0.181 nm (b) Calculate the attractive force between a pair of Ca2+ and S2- ions that just touch each other. Assume the ionic radius of the Ca2+ ion to be 0.106nm and that of the S2-ion to be 0.184nm 7. (a) Calculate the net potential energy for a K+Cl- pair by using the b constant calculated from Prob. 6.(a). Assume n=9.0. (b) Calculate the net potential energy for a Ca2+S2- ion pair by using the b constant calculated from Prob. 6.(b). Assume n=9.0