$59.$ Which equations are utilized to determine the minimum reflux ratio for a desired separation?

$-$ A$)$ McCabeThiele equations

$-$ B$)$ PonchonSavarit equations

$-$ C$)$ Underwood equations

$-$ D$)$ Fenske equations

$60.$ What does the term "total reflux" imply in distillation operations?

$-$ A$)$ The distillation column is operating without any distillate withdrawal.

$-$ B$)$ The column operates at its lowest possible reflux ratio.

$-$ C$)$ All of the feed is vaporized instantly.

$-$ D$)$ The reflux ratio is optimized for energy efficiency.

$61.$ The concept of minimum reflux ratio is critical because:

$-$ A$)$ It marks the point where additional stages will not improve separation.

$-$ B$)$ It represents the lowest reflux ratio at which the desired separation can be achieved.

$-$ C$)$ It is the most cost$-$effective operating point.

$-$ D$)$ It indicates the highest possible purity of the distillate.

$62.$ Multiple feeds in a distillation column are used to:

$-$ A$)$ Enhance the column's flexibility in handling various feed compositions.

$-$ B$)$ Increase the separation efficiency for multi$-$component feeds.

$-$ C$)$ Reduce the column's operating costs significantly.

$-$ D$)$ Simplify the column design and construction.