Carbon dioxide is diffusing through nitrogen in one direction at atmospheric pressure and 0°C. The mole fraction of CO₂ at point A is 0.2; at point B. 3 m away, in the direction of diffusion, it is 0.02. Diffusivity D_u is 0.144 cm²/s. The gas phase as a whole is stationary; that is, nitrogen is diffusing at the same rate as the carbon dioxide, but in the opposite direction. 

(a) What is the molal flux of CO₂, in kilogram moles per square meter per hour?

(b) What is the net mass flux, in kilograms per square meter per hour?

(c) At what speed, in meters per second, would an observer have to move from one point to the other so that the net mass flux, relative to him or her, would be zero?

(d) At what speed would the observer have to move so that, relative to him or her, the nitrogen is stationary?

(e) What would be the molal flux of carbon dioxide relative to the observer under condition (d)?