Fractional distillation is used to separate mixtures with similar boiling points because it uses a fractionating column to provide repeated vaporization and condensation.

• A. True
• B. False
• C. Not necessary
• D. It uses filtration

Answer: (A)

The idea being tested is that a fractionating column makes fractional distillation effective for mixtures with close boiling points by enabling repeated vaporization and condensation. The column provides a large surface area so vapor rising from the boiling flask condenses and revaporizes multiple times as it moves upward. With each cycle, the more volatile component tends to stay in the gas phase and move higher, while the less volatile part tends to condense and return downward. After many of these vaporization-condensation steps, the vapor that reaches the top becomes enriched in the component with the lower boiling point, giving a much purer distillate than simple distillation. This is exactly why fractional distillation is used when boiling points are similar. Filtration isn’t involved in this process and doesn’t explain the improved separation, and saying it’s not necessary ignores why the column is helpful in the first place.