Question

The fractional distillation of coal tar yields:
A.) Carbon disulphide
B.) Carbon tetrachloride
C.) Kerosene oil
D.) Benzene

Answer 1

Hint: Fractional distillation is a process used for the separation of two liquid mixtures which have a small difference in their boiling points. Fractional distillation separates a mixture into a number of different parts, called fractions.

Complete step by step answer:
Fractional distillation is the separation of a mixture into its component parts, or fractions. Chemical compounds are separated by heating them to a temperature at which one or more constituents of the mixture will vaporize. Generally, the component parts have boiling points that differ by less than 25°C from each other under atmospheric pressure, i.e. 1 atmosphere. If the difference in boiling points is greater than 25 °C, a simple distillation process is used.
Coal tar is the by-product produced in the manufacturing of coke. Coal tar comes from bituminous coal used in the distillation process. It is a volatile substance, important for its organic chemical constituents (coal-tar crudes), which are extracted by further distillation. These include xylene, toluene, naphthalene and phenanthrene, and are the basic ingredients for the synthesis of many products, such as explosives, drugs, dyes and perfumes.
Fractional distillation of coal tar mainly produces aromatic hydrocarbons like benzene, creosotes, naphthalene, anthracene, carbolic and cresylic acids, pyridine and pitch.

Hence, the correct answer is (D) Benzene.

Note: Remember that fractional distillation is different from simple distillation. Fractional distillation is used when the difference in boiling points of the constituents is less than 25°C, otherwise simple distillation is used.