The tube in figure (a) will be more effective as a condenser in the distillation apparatus.
This is because due to the presence of beads in the tube (a) will provide more surface area as compared to the tube in which there are no beads. And, the tube with large surface area leads to effective cooling.
Thus, tube (a) will be more effective condenser in the distillation apparatus.
* A condenser condenses steam to water in a distillation process. It turns gases to liquids by cooling them.