The charge on a charged sphere is concentrated on its center .
Explanation :
The charge on a charged sphere is just concentrated in the center of a shell. We can also say that that the charges are being distributed across the charged sphere. This is totally because of the absence of the electric field. In other words, we can say that, inside a conductor, the electric field is zero.
And that is why the charges are distributed across the surface. Due to the electrostatic forces inside the nucleus or the atom, the apparent forces get cancelled and thus the electric field becomes zero.