a$)$ The rate law for the hydrogenation $($H$)$ of ethylene $($E$)$ to form ethane $($A$)$ over a cobalt$-$molybdenum

catalyst is given by$,$

Suggest a mechanism and rate$-$limiting step consistent with the above rate law. What is the most difficult

part in finding the mechanism?

$($b$)$ The exit age distribution for a reactor is given by E$($t$)=\backslash$delta $($t $4),$ where t is in seconds. A first order

liquid phase reaction $($k $=0\mathrm{.}25$ s$1$

$)$ is carried out in this reactor under steady state and isothermal conditions.

What is the mean conversion of the reactant at the exit of the reactor?