Q$4.(35)$ A tray tower is to be used to absorb $99\%$ of the ammonia from an entering gas stream $($air $+$ ammonia$)$ containing $30$mol$\%$ ummonia at $30C$ and $1$ atm.

a$)$ What is the minimum flow $L^{\text{'}}?$

b$)$ Calculate the number of theoretical trays needed using $1\mathrm{.}5$ times factor the minimum plot the equilibrium and operating lines: Assume the entering gas flow rate is $1$ mol. The vapor$-$liquid equilibria can be represented by $Y_A=1\mathrm{.}74x_A.$ Draw the operating$-$line by obtaining four points.n