Question

The total number of isomers in ${C_6}{H_3}C{l_3}$ is :
A.) two
B.) three
C.) four
D.) five

Answer 1

Hint:The isomers are those molecules which have the same molecular formula but they have different structural formulas. The compound ${C_6}{H_3}C{l_3}$ has the chemical name as trichlorobenzene.

Complete step by step answer:
As we know that the given compound ${C_6}{H_3}C{l_3}$ has the chemical name of trichlorobenzene. In trichlorobenzene, there is one benzene ring and three chlorine atoms are substituted on the place of three hydrogens of different carbons of the benzene ring. In total, trichlorobenzene contains six carbons, three hydrogen atoms and three chlorine atoms.
As we know that isomers are those compounds which have the same molecular formula but their structures are different from each other. Therefore, to get the isomers of trichlorobenzene, we will only change the positions of chlorine atoms that are substituted on the benzene ring. According to this, there can be only three different ways in which the chlorine can be attached to the benzene ring without changing the chemical formula of the compound. Therefore, the three isomers of the trichlorobenzene are:
$1$.) $1,2,3 - $trichlorobenzene
$2$.) $1,2,4 - $trichlorobenzene
$3$.) $1,3,5 - $trichlorobenzene
There structure can be represented as:

In the $1,2,3 - $trichlorobenzene, the chlorine atoms are attached at carbon number $ - 1$, carbon number $ - 2$, and carbon number $ - 3$. In the $1,2,4 - $trichlorobenzene, the chlorine atoms are attached at carbon number $ - 1$, carbon number $ - 2$, and carbon number $ - 4$. In the $1,3,5 - $trichlorobenzene, the chlorine atoms are attached at carbon number $ - 1$, carbon number $ - 3$, and carbon number $ - 5$. All these isomers are different from each other by the position of chlorine atoms attached to the benzene ring.
As trichlorobenzene (${C_6}{H_3}C{l_3}$) has three isomers.

Hence, B.) is the correct option.

Note:
As trichlorobenzene is used as a solvent in organic chemistry beside it, trichlorobenzene is also used for the purpose of dyes because it can absorb into the polyester fibers and as an intermediate in the production of herbicides and pesticides also.