8.5 the answer is and replace the areas
I don't know what to do but I think it is #1
F = kq2 / r2
q = ne
F = k(ne)2 / r2
n = âš(r2F / ke2) = (r/e) âš(F/k)
k = 9 x 109 Nm2/C2
e = 1.6 x 10-19 C
n = [(4.2 x 10-10) / (1.6 x 10-19)] âš[(5.2 x 10-9) / (9 x 109)] ≅ 1.995 ≅ 2
15 + 7 + 9 + 7 + 4 + 4 + 3 + 3 = 52
