Q1: Packed column distillation is limited to the column __________ metres.

ANS:C - both (a) & (b)

Packed column distillation is not strictly limited to a specific height or diameter. Instead, the design considerations for packed columns depend on various factors such as the specific separation requirements, efficiency targets, and operating conditions. While there are practical constraints on the height and diameter of packed columns, these constraints are not universally defined as "height < 6" or "diameter < 0.6". The height of a packed column is typically determined based on factors such as the desired separation efficiency, pressure drop limitations, and economic considerations. Higher columns may provide better separation but can be more expensive to construct and operate. Similarly, the diameter of a packed column depends on factors such as the flow rates of the liquid and vapor phases, the characteristics of the packing material, and the allowable pressure drop. Smaller diameters may result in higher pressure drops and reduced capacity, while larger diameters may increase costs and require more space. Therefore, packed column distillation is not strictly limited by a specific height or diameter criterion like "height < 6" or "diameter < 0.6". Instead, the design of packed columns is tailored to meet the specific requirements of the separation process.