please check answer for part A and solve part B

thank you I will upvote

6) Ionic radius of Ba2+=0.143rm,S2=0.174nm. If a pair of Ba2+ and S2 ions are just toaching, calculate attractive force between them. A) Fatt=40r2z1z20=8.851012r=.143+.174nmz1=2(1.6021019)z1=3.02041019z2=2(1.6021019)z2=3.2041019fattr=9109N b) If net attractive trepulsive forces between Ba2++S2 ions are in balance in the previous problem, calculate the net potential energy for a Baa2+S2-ion pair by using the b constant (Assume n=10.5 )