ANS:A - changes the relative volatility of the original components.

The solvent used in extractive distillation should meet certain criteria to effectively separate the components of a mixture. Let's analyze each statement:

1. Solvent used in extractive distillation changes the relative volatility of the original components.
   • True. The primary function of the solvent in extractive distillation is to alter the relative volatility of the original components, making their separation easier. By adding the solvent, the relative volatility between the components and the solvent is adjusted, allowing for improved separation.
2. Solvent used in extractive distillation should be of high volatility.
   • True. A solvent with high volatility is desirable in extractive distillation because it should be easily separated from the mixture after the distillation process. High volatility ensures that the solvent can be efficiently recovered from the distillation bottoms, leaving behind the separated components.
3. Solvent used in extractive distillation should form azeotropes with the original components.
   • False. While some solvents used in extractive distillation may form azeotropes with the original components, this is not a universal requirement. The main purpose of the solvent is to change the relative volatility of the components, and this can be achieved without forming azeotropes. Solvents that form azeotropes with the components may provide additional separation capabilities, but it is not a strict requirement for all solvent choices.