The oxygen needs of fish in aquariums are usually met by forcing air to the bottom of theaquarium by a compressor. The air bubbles provide a large contact area between the water andthe air, and as the bubbles rise, oxygen and nitrogen gases in the air dissolve in water whilesome water evaporates into the bubbles. Consider an aquarium that is maintained at roomtemperature of $25$ oC at all times at $1$ atm. The air bubbles are observed to rise to the free surfaceof water in $2$ s$.$ If the air entering the aquarium is completely dry and the diameter of the airbubbles is $4$ mm$,$ determine the mole fraction of water vapor at the center of the bubble whenit leaves the aquarium. Assume no fluid motion in the bubble so that water vapor propagates inthe bubble by diffusion only. The mass diffusivity of water vapor in air at $25$ oC is $2\mathrm{.}50$x$10-5$m$2/$s$.$