Which process is used to separate crude oil into components?

• A. Fractional distillation
• B. Simple distillation
• C. Fractional crystallization
• D. Filtration

Answer: (A)

Separating crude oil relies on differences in boiling points to split a complex liquid into many fractions. When crude oil is heated, its various hydrocarbons vaporize at different temperatures. The vapors rise up a fractionating column that has a temperature gradient and many trays. Heavier fractions with higher boiling points condense lower down, while lighter fractions with lower boiling points rise higher and condense near the top. This creates distinct fractions such as LPG, petrol, kerosene, diesel, and heavy fuel oil, each made up of hydrocarbons with similar boiling points.

Other methods wouldn’t achieve this: simple distillation can separate out components only if their boiling points are very different, producing too few fractions; fractional crystallization is for solid crystals forming from a solution, not for separating mixtures of liquids; filtration is for removing solids from liquids, not for separating a mixture of liquids based on boiling behavior.