Solve the all parts of given question:
Question: A total electric charge of 2.50nC is distributed uniformly over the surface of a metal sphere with a radius of 28.0 cm. The potential is zero at a point at infinity.
Part A: Find the value of the potential at 55.0cm from the center of the sphere.
Part B: Find the value of the potential at 28.0cm from the center of the sphere.
Part C: Find the value of the potential at 14.0cm from the center of the sphere.
Please explain your each step in detail for above question.