Total number of possible structural isomers of `C_5H_11Br`.

Explanation

To determine the total number of possible structural isomers of \( C_5H_{11}Br \), we can follow these steps:

### Step 1: Understand the molecular formula
The molecular formula \( C_5H_{11}Br \) indicates that we have:
- 5 carbon atoms (C)
- 11 hydrogen atoms (H)
- 1 bromine atom (Br)

### Step 2: Identify the carbon skeletons
We can start by identifying the different carbon skeletons that can be formed with 5 carbon atoms. The carbon skeletons can be straight-chain or branched.

1. **Straight-chain structure (n-pentane)**:
- \( CH_3-CH_2-CH_2-CH_2-CH_3 \)

2. **Branched structures**:
- Isomers can be formed by branching the carbon chain. For 5 carbon atoms, we can have various configurations:
- 2-methylbutane: \( CH_3-CH(CH_3)-CH_2-CH_3 \)
- 3-methylbutane: \( CH_3-CH_2-CH(CH_3)-CH_3 \)
- 2,2-dimethylpropane: \( C(CH_3)_2-CH_2-CH_3 \)
- 2,3-dimethylbutane: \( CH_3-CH(CH_3)-CH(CH_3)-CH_3 \)

### Step 3: Add the bromine atom
Next, we will add the bromine atom to the different carbon skeletons. The bromine can be attached to different carbon atoms in each of the structures identified above.

### Step 4: Count the structural isomers
1. **For n-pentane**: Br can be on any of the 5 carbon atoms.
2. **For 2-methylbutane**: Br can be on the main chain or the methyl group.
3. **For 3-methylbutane**: Similar to 2-methylbutane, consider positions.
4. **For 2,2-dimethylpropane**: Br can only be attached to the main carbon.
5. **For 2,3-dimethylbutane**: Multiple positions for Br.

### Step 5: List all unique structures
After considering all the possible placements of the bromine atom on each carbon skeleton, we can list the unique structural isomers.

1. **n-Pentyl bromide**
2. **2-Methylbutyl bromide**
3. **3-Methylbutyl bromide**
4. **2,2-Dimethylpropyl bromide**
5. **2,3-Dimethylbutyl bromide**
6. **3-Bromopentane**
7. **2-Bromopentane**
8. **1-Bromopentane**

### Conclusion
After analyzing all the possibilities, we find that the total number of possible structural isomers of \( C_5H_{11}Br \) is **8**.

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