Consider liquid n-hexane in a 50-mm-diameter graduated cylinder. the distance from the liquid-gas interface to the top of the cylinder is 20 cm. the steady-state n-hexane evaporation rate is 8.2 x 10-8kg/s and the n-hexane mass fraction at the liquid-air interface is 0.482. the diffusivity of n-hexane in air is 8.0 x 10^-4 m^2/s. determine the mass flux of n-hexane vapor.

15. which of the following is not human-caused groundwater pollution? a. water in an aquifer dissolves elements such as arsenic and mercury from surrounding rock. b. water in an aquifer is contaminated by leachate that seeps into the ground from a landfill. c. water in an aquifer becomes polluted with chemicals used in hydraulic fracturing, or fracking. d. water in an aquifer absorbs harmful bacteria from the drainage field of a septic tank.