4.10 Steel spheres (5 mm radius) that have a uniform concentration of carbon equal to 1.0103mol/cm3 will be further carburized by exposing them to a gas containing carbon monoxide at 900C. The concentration of carbon monoxide in the gas is such that the sphere surface is continuously kept at a carbon concentration equal to 4.5103mol/cm3 in the steel. The diffusivity of carbon in the steel is 2.01011m2/s. a. At the end of the process, the spheres will be suddenly cooled in an oil bath, which essentially stops diffusion by binding the carbon to the iron mineral in the steel. If the process is designed to end when the carbon concentration in the steel reaches 3.5103mol/cm3 at a distance of 2mm from the sphere surface, determine the time required for the process. b. What is the total carbon content in a steel sphere at the end of the process (moles)? c. What is the minimum concentration of carbon in the sphere at the end of the process