A gas stream containing $95 \mathrm{~mol} \% \mathrm{CO}_{2}$ and $5 \mathrm{~mol} \%$ ethanol is to be scrubbed with pure water in a counter-current, isothermal absorption column to remove ethanol. The desired composition of ethanol in the exit gas stream is $0.5 \mathrm{~mol} \%$. The equilibrium mole fraction of ethanol in the gas phase, $y^{*}$, is related to that in the liquid phase, $x$, as $y^{*}=2 x$. Assume $\mathrm{CO}_{2}$ is insoluble in water and neglect evaporation of water. If the water flow rate is twice the minimum, the mole fraction of ethanol in the spent water is
- $0.0225$
- $0.0126$
- $0.0428$
- $0.0316$