Their are 4 stereo isomres in this compound 2 geometrical isomers and 2 optical isomers

Number of stereoisomerism in CH3-CH=CH-CH2-CHBr-CH3:
There are two main types of stereoisomerism: geometric isomerism and optical isomerism. Geometric isomerism occurs when there is restricted rotation around a double bond or a ring, while optical isomerism occurs when a molecule has a chiral center.

Geometric Isomerism:
Geometric isomerism can occur when there is a double bond present in the molecule. In the given molecule, there is a double bond between the second and third carbon atoms (CH3-CH=CH-CH2-CHBr-CH3). Geometric isomerism arises due to the restricted rotation around this double bond.

To determine the number of geometric isomers, we need to identify the different arrangements of substituents on each carbon of the double bond. In this case, the substituents on the second carbon are CH3 and CH2-CHBr-CH3, while the substituents on the third carbon are CH-CH2-CHBr and CH3.

There are two possible arrangements for the substituents on the second carbon:
1. CH3 on the same side as CH3-CH2-CHBr-CH3 (cis-isomer)
2. CH3 on the opposite side as CH3-CH2-CHBr-CH3 (trans-isomer)

Similarly, there are two possible arrangements for the substituents on the third carbon:
1. CH-CH2-CHBr on the same side as CH3 (cis-isomer)
2. CH-CH2-CHBr on the opposite side as CH3 (trans-isomer)

Therefore, there are a total of four geometric isomers possible for CH3-CH=CH-CH2-CHBr-CH3.

Optical Isomerism:
To determine if the molecule exhibits optical isomerism, we need to check if it contains a chiral center. A chiral center is a carbon atom that is bonded to four different substituents.

In the given molecule, none of the carbon atoms have four different substituents. Therefore, there are no optical isomers in CH3-CH=CH-CH2-CHBr-CH3.

Summary:
In summary, the molecule CH3-CH=CH-CH2-CHBr-CH3 exhibits four geometric isomers due to the restricted rotation around the double bond. However, it does not possess any chiral centers, and therefore, does not exhibit optical isomerism.