Q1: The reason for preferring packed towers over plate towers in distillation practice is that the packed tower operation gives

ANS:C - low pressure drop and low hold up.

Packed towers are not typically preferred for low pressure drop and low hold-up. Instead, they are preferred for low pressure drop and high hold-up. In a packed tower, the pressure drop is relatively low because the liquid flows through the packed bed with minimal resistance due to the open structure of the packing material. This low pressure drop is advantageous as it reduces the energy required to pump the liquid through the tower. Additionally, packed towers have a high hold-up, meaning they can retain a significant amount of liquid within the packed bed. This high hold-up allows for better contact between the liquid and vapor phases, which is essential for efficient mass transfer and separation in distillation processes. Therefore, the correct reason for preferring packed towers over plate towers in distillation practice is low pressure drop and high hold-up.