Physics problem

[mustang]

Problem 19.
At the point of fission, a nucleus of 235_U that has 92 protons is divded into two smaller spheres, each of which has 46 protons and a radius of 5.9*10^-15m. what is the magnitude of the repulsive force pushing these two spheres apart? Use 8.99*10^9 N*m^2/C^2.
Note: How can you find the distance if the problem only the radius?

[HallsofIvy]

I would assume the two spheres are meant to be touching each other so that you can assume to point charges separated by 2(5.9*10^-15m)=
11.8*10-15m.