Question

How many structural isomers of molecular formula ${C_3}{H_6}BrCl$ ?
a.) 4
b.) 5
c.) 6
d.) 7

Answer 1

The structural isomers are the ones which differ in the structure of the molecule. These are the three carbon molecules. By drawing the structure and replacing the Br and Cl with hydrogen, we can get the structural isomers.

Complete answer:
First, let us see what structural isomers are.
The isomers are those species that contain the same molecular formula. The structural isomers are the ones which differ in the structure of the molecule. It is also called constitutional isomers as it is due to different constitutions of the carbon bonds.
The structural isomers are of three different types. The chain isomers in which there is a difference in carbon chains. The other one are the position isomers in which the position of the substituted groups different. The ${C_3}{H_6}BrCl$ have positional isomers. The third one are functional group isomers where there are different functional groups that are formed from the same type of atoms. The ethers, carboxylic acids, aldehydes and ketones form functional isomers.
The ${C_3}{H_6}BrCl$ is a three carbon chain. The various structural isomers that can be drawn are -

So, the total structural isomers that could be drawn are 5.

Thus, the option b.) is the correct answer.

Note:
It must be noted that structural isomers have the same number of atoms of each type. There is a difference in connectivity of atoms. There is another form known as stereoisomers. These molecules have the same molecular formula but differ in arrangement of atoms in 3D space.