Explanation:
Before proceeding, it is important to understand that both the standard distillation and fractional distillation are separation techniques that operates based on the difference in boiling points of the liquids.
The main difference is fractional distillation is used to separate liquids with closer boiling point like in the case of crude oil distillation while simple distillation is used to separate liquids with boiling point gaps of at least 50 degrees.
So the condition which fractional distillation should be used is when the liquids to be separated have a close boiling point differences,
