An ideal liquid mixture of benzene and toluene $(50\%$ each$)$ is used in a plant at $27$ deg. centigrade and $1$atm$.$ Determine a$)$ the mixture TLV$,$ b$)$ the evaporation rate per unit area for this mixture, and c$)$ the ventilation rate required to keep the concentration below the TLV if the drum bung diameter is $5\mathrm{.}1$cm$.$ Assume the ventilation quality within the vicinity is average.