Consider an organic compound DCB which is usually used as a disinfectant. Its molecular weight is $200\frac{g}{m}ol$; its vapor pressure is $0\mathrm{.}02$atm at $25C$ and under this pressure its saturated water solubility is $5\mathrm{.}0{10}^{-4}mo\frac{l}{L}.$ In a lake, the measured concentration of DCB is $10n\frac{g}{L}$ and its concentration in the air above the lake is $1n\frac{g}{L}.$ Given that the wind speed above the lake is $20c\frac{m}{s},$ what is the flux of DCB into or out of the lake? If the flow rate of DCB through the water surface keeps constant, how much is the evaporative half$-$life of DCB$?$ The area of the lake is $100k{m}^2$ and the average depth is $50m.$