A uniformly charged insulating sphere is in a vacuum. Its radius

R is 30$30$ mm.$.$ The permittivity of the material of the sphere is the same as that of vacuum. When the zero point of potential is chosen infinitely far from the sphere, the potential at the center of the sphere is +75$+75$ kV.$.$

a)$)$ What is the total charge of the sphere?

b)$)$ What work does the electric field do when an electron is released from infinity and allowed to move to the surface of the sphere?

c)$)$ What is the velocity of the electron when it strikes the surface of the sphere?