Carbon is allowed to diffuse through a steel plate 15 mm thick. the concentrations of carbon at the two faces are 0.65 and 0.30 kg c/m3 fe, which are maintained constant. if the preexponential and activation energy are 6.2 x 10-7 m2/s and 80,000 j/mol, respectively, compute the temperature at which the diffusion flux is 1.43 x 10-9kg/m2-s.