Refer to the attached Txy diagram for vapor$/$liquid equilibrium for ethanol$(1)/$ethyl acetate$(2)$ at $100$kPa. Respond to the following questions with a few short sentences and some simple calculations. Feel free to copy the graph and draw on it to prove your answer.

$($a$)$ A mixture of ethanol and ethyl acetate is heated in a closed system at $100$kPa to a temperature of $74C,$ and two phases are observed to be present. What are the possible compositions of the liquid and vapor phases?

$($b$)$ Consider a mixture with $1=0\mathrm{.}70,$ initially at $70C$ and $100$kPa. Describe the evolution of phases and phase compositions as the temperature is gradually increased to $80C.$

$($c$)$ Consider a mixture with $1=0\mathrm{.}20,$ initially at $80C$ and $100$kPa. Describe the evolution of phases and phase compositions as the temperature is gradually reduced to $70C.$

$($d$)$ Consider a closed vessel initially containing $1$mol of pure ethyl acetate at $74C$ and $100$ kPa. Imagine that pure ethanol is slowly added at constant temperature and pressure until the vessel contains $1$mol ethyl acetate and $9$mol ethanol. Describe the evolution of phases and phase compositions during this process. Comment on the practical feasibility of carrying out such a process. What sort of device would be required?