Advanced Physics $-$ Electronstatic

Please kindly answer these $2$ exercises with the clear steps and explanation, many many thanks!

Exercise $3$

Consider a solid copper sphere having a mass corresponding to one mole. Let us admit that we can remove its free electrons, numbering one electron per atom. Calculate:

a$)$ the radius of the sphere and its charge

b$)$ the electric force between two identical spheres separated by a distance of $60$cm Ex $6$

We will admit that in a hydrogen atom, the electron has a circular trajectory around the proton. The radius of the orbit is therefore $5\mathrm{.}31011$m$.$ Calculate:

a$)$ the force of attraction between the proton and the electron; compared with the weight of the atom

b$)$ the speed of the electron in its orbit; compared with the speed of light