Question

The correct decreasing order of boiling points of petroleum fractions is:
A) Petrol > lubricating oil > diesel > LPG
B) Lubricating oil > diesel > petrol > LPG
C) Petrol > diesel > LPG > lubricating oil
D) Lubricating oil > Petrol > diesel > LPG

Answer 1

Hint: Recall the fractional distillation technique for refining of crude petroleum. Fractional distillation process separates the components of mixture into a number of fractions in increasing order of their boiling points and molecular mass.

Complete step by step answer:
Crude petroleum is a viscous mixture of a number of hydrocarbons. Refining is the common process to obtain useful products of commercial and industrial importance from crude petroleum. Refining processes include fractional distillation methods or techniques. This technique involves the separation of the components of mixture into a number of fractions in the increasing order of their boiling points and molecular mass. In refineries, mixture is introduced into a tall fractionating column and heated, which results in the separation of different fractions. More volatile fractions with lower boiling point are collected at the top of the column whereas the less volatile fractions having higher boiling point get collected at the bottom of the column.
Below table lists different fractions along with their boiling point:

S.NO.	Fractions	Boiling point
1	LPG	< 20
2	Petrol	> 40 - 180
3	Diesel	> 250 - 400
4	Lubricating oil	> 400

 Thus, now we can write the decreasing order of boiling points of different petroleum fractions as: Lubricating oil > diesel > petrol > LPG.
So, the correct answer is “Option B”.

Note: It should be noted that during the refining process of crude petroleum, a residue is generally obtained known as bitumen, which is used as a binding material for road surfaces and also as a roofing material.