Which of the following is a primary alkyl halide ?

Options

A. `C_(6)H_(5)CHCICH_(3)`
B. `CH_(3)CHCICH_(2)CH_(3)`
C. `(CH_(3))_(2)CHCH_(2)Cl`
D. `(CH_(3))_(3)"CCl"`

Answer

To determine which of the given options is a primary alkyl halide, we need to understand the definitions and characteristics of primary, secondary, and tertiary alkyl halides.

### Step-by-Step Solution:

1. **Understanding Alkyl Halides**:
- Alkyl halides are compounds derived from alkanes by replacing one or more hydrogen atoms with halogen atoms (F, Cl, Br, I).
- The classification of alkyl halides depends on the number of carbon atoms attached to the carbon that bears the halogen.

2. **Definitions**:
- **Primary Alkyl Halide**: The carbon atom bonded to the halogen is attached to only one other carbon atom.
- **Secondary Alkyl Halide**: The carbon atom bonded to the halogen is attached to two other carbon atoms.
- **Tertiary Alkyl Halide**: The carbon atom bonded to the halogen is attached to three other carbon atoms.

3. **Analyzing the Options**:
- Let's analyze each of the provided options to identify which one is a primary alkyl halide.

**Option A**: C6H5-CH=CH-I-CH3
- This structure has a double bond and an iodine (I) attached to a carbon that is also part of a double bond. This indicates that it is a vinylic compound, not an alkyl halide.

**Option B**: C6H5-CH=CH-I
- Similar to Option A, this structure also has a double bond with iodine attached to a carbon involved in that double bond. Thus, it is also vinylic.

**Option C**: CH3-CH2-CH2-Br
- In this structure, the carbon bonded to bromine (Br) is attached to only one other carbon (the CH2 group). This matches the definition of a primary alkyl halide.

**Option D**: (CH3)3C-Cl
- Here, the carbon bonded to chlorine (Cl) is attached to three other carbon atoms (the three methyl groups). This is a tertiary alkyl halide.

4. **Conclusion**:
- Based on the analysis, the only structure that qualifies as a primary alkyl halide is **Option C**: CH3-CH2-CH2-Br.

### Final Answer:
**Option C** is the primary alkyl halide.