Q1: Back-trapping in a distillation column

ANS:B - decreases tray efficiency.

Back-trapping in a distillation column typically decreases tray efficiency. Here's why:

• Back-trapping occurs when liquid flows down a tray in a distillation column but is hindered from flowing down further by a buildup of liquid on the tray above.
• This buildup of liquid prevents efficient downflow of liquid, which can lead to reduced surface area for vapor-liquid contact and decreased mass transfer efficiency.
• As a result, back-trapping tends to decrease the efficiency of the tray in promoting vapor-liquid contact and separation of components.
• Back-trapping does not necessarily affect pressure drop or improve vapor-liquid contact; instead, it hinders the proper functioning of the tray by impeding the flow of liquid.