Question

The fractional distillation of petroleum is shown. Which fraction is the least volatile?
A. Bitumen
B. Diesel oil
C. Gasoline fraction
D. Refinery gas

Answer 1

Petroleum is also known as crude oil. It is found in rocks. It is a non-renewable energy source. The gas oil is also called fuel oil. Boiling point is the temperature at which the Vapor pressure of the substance becomes equal with the atmospheric pressure. If the atmospheric pressure becomes lower the boiling point will also get low and vice-versa.

Complete step by step answer:
Crude oil is nothing but a mixture of many miscible different compounds with different structures. These compounds are not chemically combined. This mixture can be separated by the fractional distillation, where the fractions of oils are extracted based on their boiling point. These fractions can be used for many purposes as a source of energy. These fractions are nothing but hydrocarbon chain compounds with a large number of carbons. The boiling points of these fractions depend upon their molecular mass as their intramolecular force of attraction is very low. These liquid fractions can be vaporized under heating without decomposition of their structures. Then after condensation of those vapors, fractions of crude oil can be collected separately. Fractions with lower boiling points get separated before higher boiling point fractions. So, considering the diagram given in the question, among all fractions of crude oil, Bitumen has the highest boiling point.

So, the correct option is A.

Note: When material boils, they are converted into a gaseous state. Petroleum is also known as crude oil, is a mixture of many miscible different compounds with different structures. Therefore, it does not have a single boiling point. To determine the quality of the crude oil boiling point test is used. In this test, this oil is boiled at a constant temperature to determine the number of ignitable hydrocarbons (petrol, kerosene, diesel, etc.) in the crude oil. The gas oil is also called fuel oil has the highest boiling point among all fractions.