Q $2$: Ammonia is recovered from ammonia air mixture containing $5\%$ by volume of ammonia by scrubbing with fresh water in a counter current plate absorption tower. The gas feed into the bottom of the tower and in the exit gas from the top the ammonia exert a partial pressure of $0\mathrm{.}012K\frac{N}{m^2}.$ The water fed to the top of the tower is free from NH$3.$ For this system Henrys law hold and $Ye=1\mathrm{.}35x$ and the process take place at $293k$ and $101\mathrm{.}3K\frac{N}{m^2}.$ If the water rate is $0\mathrm{.}65k\frac{g}{m^2}s$ and the air rate is $0\mathrm{.}4k\frac{g}{m^2}s$ and KOGa$=0\mathrm{.}001$kmo$\frac{l}{m^3}$skpa.

Calculate the number of theoretical plates required.