ANS:D -

In continuous distillation, the internal reflux ratio (𝑅𝑖Ri​) and the external reflux ratio (𝑅𝑒Re​) are related by the following equation: 𝑅𝑖=𝐷𝐵+𝐷×𝑅𝑒Ri​=B+DD​×Re​ Where:

• 𝑅𝑖Ri​ is the internal reflux ratio, which represents the ratio of the reflux returned to the column to the distillate removed from the column within the column itself.
• 𝑅𝑒Re​ is the external reflux ratio, which represents the ratio of the reflux returned to the column to the distillate removed from the column external to the column (usually in a condenser).
• 𝐷D is the rate of distillate removed from the column.
• 𝐵B is the rate of bottoms (residue) removed from the column.

This equation shows that the internal reflux ratio is a fraction of the external reflux ratio, with the fraction being determined by the ratio of distillate to the sum of distillate and bottoms flow rates. This relationship ensures that the total reflux returning to the column is distributed appropriately between the internal and external reflux streams.