$68.$ Air at a rate of $0\mathrm{.}100$ kmol$/$min is bubbled through a column of liquid C$6$H$14$ at $25\backslash$deg C$.$ The gas stream leaving the column contains $10\mathrm{.}0$ mol $\%$ C$6$H$14$ vapor. If the cylindrical column has an over diameter of $55$ cm and was initially filled with liquid C$6$H$14$ to a level of $175$ cm$.$ Determine the rate of evaporation of C$6$H$14.$