Steady-state molecular diffusion illustration (GATE 2016)

In this video, I am going to solve a numerical comparing two different cases of steady-state molecular diffusion which I had taken from the chemical engineering GATE paper of the year 2016. Consider the following two cases for a binary mixture of ideal gases P & Q under steady state conditions. In case 1, the diffusion of P occurs by equimolal counters diffusion of Q. In case 2, the diffusion of P occurs through non diffusing Q. In both the cases, the total pressure is 500 kPa and the partial pressure of P at two points separated by a distance of 0.1 mm are 50 kPa and 25 kPa. Assume that the Fick's first law of diffusion is applicable. What is the ratio of molar flux of P in case 1 to that in case 2 ?