ANS:A - differential

Differential distillation is a distillation process used to separate components of a liquid mixture based on their differences in volatility, or boiling points. Unlike batch distillation, where the separation occurs in distinct stages or batches, in differential distillation, the separation process happens continuously. Here's how differential distillation works:

1. Continuous Feed: In differential distillation, a continuous feed of the liquid mixture to be separated is introduced into the distillation column. This feed typically enters the column at a specific point, often near the top or bottom, depending on the design of the column.
2. Vaporization: As the feed enters the column, it is heated, causing it to vaporize. The vapor rises through the column, while the remaining liquid (residue) continues to flow downward.
3. Fractionation: Within the distillation column, there are several stages or trays (or packing material) that facilitate the separation process. Each stage provides a different temperature and composition gradient. As the vapor rises through the column, it comes into contact with these stages. Components with lower boiling points vaporize more readily and rise higher in the column before condensing, while those with higher boiling points remain in the liquid phase and flow downward.
4. Condensation: At the top of the column, the vapor encounters a condenser, where it is cooled and condensed back into a liquid. This condensed liquid, known as the distillate, contains the more volatile components of the mixture.
5. Collection: The distillate is collected separately from the residue, which contains the less volatile components. The residue may undergo further processing or be recycled back into the column for additional separation.

Differential distillation allows for the continuous separation of liquid mixtures into their individual components based on their boiling points. It is widely used in industries such as petroleum refining, chemical processing, and alcohol production, where precise control over product purity is essential.