Final answer:
Fractional distillation separates crude oil components based on boiling points but cannot replace cracking, which breaks down heavier molecules into lighter ones.
Step-by-step explanation:
The student's question pertains to the processes applied to crude oil in order to obtain different products. Fractional distillation and cracking are both processes employed in the refining of petroleum, but they serve different purposes and cannot be used interchangeably.
Fractional distillation is used to separate the components of crude oil based on their different boiling points, with the lighter components having lower boiling points and rising to the top of the distillation column, while the heavier components with higher boiling points remain at the bottom.
On the other hand, cracking is a process that breaks down heavier hydrocarbon molecules into lighter ones, which is often necessary when there is high demand for lighter products, like gasoline, than can be produced through distillation alone.
Therefore, fractional distillation cannot be used instead of cracking, as they are complementary processes in petroleum refining.