$4.$Flash distillation is most effective when:

A$)$ The feed is a multi$-$component mixture.

B$)$ There is a large difference in volatility between the components.

C$)$ The components have similar volatilities.

D$)$ The feed is at atmospheric pressure.

The McCabeThiele method assumes:

A$)$ Constant relative volatility.

B$)$ Variable relative volatility.

C$)$ No reflux is used.

D$)$ Infinite stages.

The Fenske equation is useful for:

A$)$ Estimating the minimum reflux ratio.

B$)$ Determining the number of stages at total reflux.

C$)$ Calculating the heat duty of the condenser.

D$)$ Designing the column diameter.

A higher relative volatility indicates:

A$)$ A more difficult separation by distillation.

B$)$ An easier separation by distillation.

C$)$ No impact on the separation process.

D$)$ That additional purification steps are needed.