A separation of A$,$ B and C is carried out using a unit process show below. The total flowrate of $P2$ is $15$ times greater than P$1.$ P$1$ is a purging stream. There is no $C$ in the top stream $($R$1)$ and no $A$ in the bottom stream $($B$2).$ The ratio of $P2$ to $R4$ and $P3$ to $B1$ are $3$:$4$ and $1$:$2,$ respectively.

a$.$ Name the process and give a mechanism$/$driving force$/$physical properties of the separation? $(5$ mark$)$

b$.$ The percentage molar composition at B$1$ stream. $(5$ mark$)$

c$.$ Obtain the entire unknown if the flowrate of $F$ is $100$kmo$\frac{l}{h}r.(15$ mark$)$

Offeas$//$ourge D$1$

$($Answers: $0\mathrm{.}2,0\mathrm{.}8,64mo\frac{l}{m}in,112mo\frac{l}{m}in,115\mathrm{.}2mo\frac{l}{m}in)$