Stereochemistry

Step 1: Understanding diastereomers.
Diastereomers are stereoisomers that are not mirror images of each other and differ in the configuration at one or more stereocenters.
Step 2: Analyzing the options.
- In option (A), the compounds are diastereomers because of the different configurations at their chiral centers.
- In option (B), the compounds are also diastereomers due to the different configurations at the stereocenters.
- In options (C) and (D), the structures do not show sufficient variation in stereochemistry to be diastereomers, as they differ only in substituents without changing the configuration at the chiral centers.
Step 3: Conclusion.
Thus, the diastereomeric pairs are (A) and (B).

Step 1: Identify chiral and geometrical centers.
- The carbon bearing –OH group is a chiral center stereocenter.
- There are three C=C bonds:
- The first (C2=C3) → can show cis–trans isomerism.
- The second (C5=C6) → can show cis–trans isomerism.
- The third (C7=C8) is part of isopropenyl ( ), which cannot show isomerism.
Step 2: Total stereogenic elements.
Thus, we have: Step 3: Total number of stereoisomers.
Step 4: Conclusion. The molecule can have 8 stereoisomers.