Question

Possible number of isomers including stereoisomers for an organic compound with the molecular formula \( C_4H_9Br \) is:

• A. 3
• B. 4
• C. 5
• D. 2

Hint:

When counting isomers, consider both structural and stereoisomers. Compounds with chiral centers contribute to additional enantiomers, increasing the total count.

Answer 1

The Correct Option is C

Step 1: Understanding Isomerism 
Isomers are compounds with the same molecular formula but different structural arrangements or spatial orientations. The molecular formula given is \( C_4H_9Br \), which corresponds to butyl bromide isomers. 

Step 2: Identifying the Isomers 
The possible structural and stereoisomers for \( C_4H_9Br \) are:
1. n-Butyl bromide (\( CH_3CH_2CH_2CH_2Br \)) - Straight-chain structure.
2. Isobutyl bromide (\( (CH_3)_2CHCH_2Br \)) - Branched structure.
3. Sec-butyl bromide (\( CH_3CHBrCH_2CH_3 \)) - Branched with a secondary carbon.
4. Tert-butyl bromide (\( (CH_3)_3CBr \)) - Branched with a tertiary carbon.
5. Sec-butyl bromide has a chiral center, leading to two enantiomers, contributing to stereoisomerism.
Step 3: Evaluating the Given Options 
- Option (1) 3: Incorrect, as it does not account for all possible isomers.
- Option (2) 4: Incorrect, as it excludes stereoisomers.
- Option (3) 5: Correct, as it includes all structural and stereoisomers.
- Option (4) 2: Incorrect, as more isomers exist.
Thus, the correct answer is 

Option (3).