(a) Derive the equation for mass transfer flux in a binary gas system under equi-molar counter diffusion.. Give the graphical representation of concentration gradient. (b) In an oxygen-nitrogen gas mixture, at 1 std. atm, 25 c, the concentration of oxygen at 2 places 2mm apart are 10 and 20 vol % respectively. Calculate the flux of diffusion of the oxygen if nitrogen DAB =1.81 X 105 m/s. (12) is on-diffusing. (1 std. atm = 1.0133 X 10 5 N/m). ww