Question

How many stereoisomers are possible for

Answer 1

Hint : As we already know that compounds which have the same molecular formula but they have different structures are termed as isomers and this phenomenon is known as isomerism. These are basically divided into two broad categories i.e. structural isomerism and stereoisomerism.

Complete Step By Step Answer:
Structural isomerism- This type of isomerism occurs due to the difference in their structures. Compounds which show this type of isomerism are known as structural isomerism. These are further subdivided into different parts such as chain isomerism, functional isomerism, positional isomerism, metamerism, Tautomerism, Ring-chain isomerism.
Stereoisomerism- This type of isomerism occurs due to the different spatial arrangement of atoms in structures. Compounds which show this type of isomerism are known as stereoisomerism. This is further divided into geometrical isomerism and optical isomerism.
Geometrical isomerism- These stereoisomers occur due to the restricted carbon- carbon double bond. It is also called as Cis- Trans isomerism.
Optical isomerism- The stereoisomers which are mirror images of each other and have different optical activity.
Now, we asked to determine the number of stereoisomers in the following compound:

First, observe whether the Plane of symmetry (POS) is present or not. In this compound, No plane of symmetry is present. Then, count the number of stereocenters. Stereocenters are those atoms which are attached to four different groups. Stereocenters are also called Chiral centers. In this compound, two stereocenters are present. Let’s see:

Formula for number of stereoisomers is as follows:
Number of stereoisomers = ${2^n}$
Where n= total number of stereocenters
Here, in this compound n = $2$
So, number of stereoisomers = ${2^2}$ = $4$
Hence, the number of stereoisomers for the given compound is $4$

Note :
Count the number of stereoisomers carefully. Also, remember that the optical isomers which are mirror images of each other are called enantiomers whereas non-mirror images are called diastereoisomers.