Density, density, density

(a) A charge – 300e is uniformly distributed along a circular arc of radius 4.00cm, which subtends an angle of 40o. What is the linear charge density along the arc?

(b) A charge – 300e is uniformly distributed over one face of a circular disk of radius 2.00 cm. What is the surface charge density over that face?

(c) A charge – 300e is uniformly distributed over the surface of a sphere of radius 2.00 cm. What is the surface charge density over that surface?

(d) A charge -300e is uniformly spread through the volume of a sphere of radius 2.00 cm. What is the volume charge density in that sphere?