Which following is primary alkyl halide alkyl halide

Options

A. `R-CH_2-X`
B. `R_2CHX`
C. `R_3C-X`
D. `R-H`

Explanation

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

### Step-by-Step Solution:

1. **Definition of Alkyl Halides**: Alkyl halides are organic compounds containing a halogen atom (F, Cl, Br, I) bonded to an alkyl group (a carbon chain).

2. **Understanding Primary Alkyl Halide**: A primary alkyl halide is one where the carbon atom bonded to the halogen is attached to only one other carbon atom (i.e., it is at the end of a carbon chain). This means that the carbon with the halogen is connected to only one alkyl group.

3. **Identifying Carbon Types**:
- **Primary (1°)**: The carbon with the halogen is attached to one other carbon.
- **Secondary (2°)**: The carbon with the halogen is attached to two other carbons.
- **Tertiary (3°)**: The carbon with the halogen is attached to three other carbons.

4. **Analyzing Options**: Without specific options provided, we would typically analyze each compound to see how many carbon groups are attached to the carbon with the halogen.
- If the carbon with the halogen is connected to one carbon, it is a primary alkyl halide.
- If it is connected to two, it is secondary.
- If it is connected to three, it is tertiary.

5. **Conclusion**: Based on the definitions and analysis, we can conclude which option is the primary alkyl halide. In this case, the only primary alternative is option no.1.