ANS:D - The capacity of a distillation coloumn is maximum at total reflux.

The wrong statement is: "Decrease in Murphree plate efficiency is an indication of entrainment in distillation column." In fact, a decrease in Murphree plate efficiency is not necessarily an indication of entrainment in a distillation column. Murphree plate efficiency is a measure of the actual separation achieved by each theoretical plate in a distillation column, and a decrease in efficiency may indicate various factors such as tray fouling, improper design, or changes in operating conditions. Entrainment, on the other hand, refers to the unwanted carryover of liquid droplets from one stage to another in a distillation column, typically caused by high vapor velocities or inadequate tray design. So, the statement is incorrect.