Out of all the possible isomers of `C_(5)H_(11)Cl`, how many are secondary in nature?
(Exclude stereoisomers if any.)

Answer

To determine how many secondary isomers exist for the molecular formula \( C_5H_{11}Cl \), we will follow these steps:

### Step 1: Identify the possible carbon skeletons
The first step is to identify the different carbon skeletons that can be formed with 5 carbon atoms. The possible structures include:
- Straight-chain (pentane)
- Branched chains (isopentane and neopentane)

### Step 2: Determine the types of carbon atoms
Next, we need to classify the carbon atoms in each structure as primary, secondary, or tertiary:
- **Primary carbon**: A carbon atom bonded to one other carbon atom.
- **Secondary carbon**: A carbon atom bonded to two other carbon atoms.
- **Tertiary carbon**: A carbon atom bonded to three other carbon atoms.

### Step 3: Draw the structures and identify secondary carbons
1. **Pentane (Straight-chain)**:
- Structure: \( CH_3-CH_2-CH_2-CH_2-CH_3 \)
- All carbons are primary except for the second and third carbons, which are secondary.

2. **Isopentane (Branched)**:
- Structure: \( CH_3-CH(CH_3)-CH_2-CH_3 \)
- The carbon in the middle (attached to two other carbons) is secondary.

3. **Neopentane**:
- Structure: \( (CH_3)_4C \)
- All carbons are primary.

### Step 4: Count the secondary isomers
From the structures analyzed:
- In pentane, there are 2 secondary carbons.
- In isopentane, there is 1 secondary carbon.
- Neopentane does not contribute any secondary carbons.

Thus, the total number of secondary carbons in the isomers is:
- **Pentane**: 2 secondary
- **Isopentane**: 1 secondary
- **Neopentane**: 0 secondary

### Conclusion
The total number of secondary isomers of \( C_5H_{11}Cl \) is **3**.