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(6 marks) Simplify the differential equation for mass transfer and Fick's flux equation according to the following assumptions: OCA V.N + RA=0 NA = -cDAYA+YANA+Nx) at 1) Steady state Unimolecular diffusion inside a tank, one dimensional in z direction without reaction. 2) Steady state, equimolar counter diffusion from spherical tablet, one dimensional diffusion in O-direction. 3) Unsteady state Unimolecular diffusion in tube reactor, dilute system, two-dimensional diffusion (r, O) directions