Fractional distillation separates petroleum by boiling point

Steps:

• Petroleum is heated and vapors rise in a fractionating column.
• Fractions with lower boiling points condense and collect higher up the column.
• Standard fractions order by increasing boiling point: gasoline (40–200°C), kerosene (150–300°C), fuel oil (>350°C).
• Butane, as a gaseous component (<0°C), is not a primary distillation fraction like the others.

Why C is correct:

• Gasoline/petrol fraction boils at the lowest temperature (40–200°C) among the listed liquid products, per the distillation process definition.

Why the others are wrong:

• A: Butane is a gas, not a standard fractional product; its bp is too low (~-0.5°C) for liquid separation.
• B: Fuel oil has the highest bp (>350°C), collected at the column bottom.
• D: Kerosene/paraffin boils higher (150–300°C) than gasoline.

Final answer: C