can you guys please explain how this question were solved

Example 23.10 Potential of hemoglobin The hemoglobin protein can be modeled as a 5.0-nm-diameter sphere. Electrophoresis measurements nd that, at a pH of approximately 8, a hemoglobin molecule in solution has a charge of 10e. a. What is the surface charge density of hemoglobin if all the charge is on the surface? b. What is the potential 1.5 nm from the surface of a hemoglobin molecule in air, in pure water, and in a mammalian cell? PREPARE We can model the hemoglobin as a charged sphere with Q = 10e = 1.6 X 1018 C. Example 23.8IE| found that the Debye length in a mammalian cell is 0.81 nm. SOLVE a. The surface of a sphere has areaA = 4::R2. If all the charge is on the surface, the surface charge density is = 0.020 cm2 Q 1.6 X 10'18 C A '7 _ _ 4::(25 >