Helium and nitrogen gas are contained in a conduit 5 mm in diameter and 0.1 m long at 298 k with a uniform constant pressure of 1.0 atm. the partial pressure of he at one end of the tube is 0.06 atm and at the other end it is 0.02 atm. the diffusivity of he in n2 is 0.687 x 10-4 m2 /s. assuming steady state in the conduit, calculate the following: a. flux of he in the conduit b. mass transfer rate of n2 in the conduit c. partial pressure of he at 0.05 m from either end