Which carbon in the following molecule has most electron density?
`{:(CH_3 - CH_2 - CH_2 - F),("III II I"):}`

Options

A. I
B. II
C. III
D. all are indentical

Answer

To determine which carbon in the molecule \( CH_3 - CH_2 - CH_2 - F \) has the most electron density, we need to analyze the effects of the electronegative fluorine atom on the carbon atoms.

### Step-by-Step Solution:

1. **Identify the Structure**:
The molecule consists of three carbon atoms (C1, C2, C3) and one fluorine atom (F) attached to the last carbon (C3). The structure can be represented as:
\[ CH_3 - CH_2 - CH_2 - F \]
Here, C1 is the first carbon (attached to three hydrogens), C2 is the second carbon (attached to two hydrogens), and C3 is the third carbon (attached to one hydrogen and one fluorine).

2. **Understand the Inductive Effect**:
The fluorine atom is highly electronegative and will withdraw electron density from the adjacent carbon (C3) due to the inductive effect. This effect is known as the -I effect (negative inductive effect), which means that electronegative atoms pull electron density towards themselves.

3. **Analyze the Distance**:
The inductive effect decreases with increasing distance from the electronegative atom. Therefore, the carbon atoms closer to fluorine (C3) will experience a stronger withdrawal of electron density compared to those further away (C1 and C2).

4. **Evaluate Each Carbon**:
- **C1**: This carbon is farthest from the fluorine and will experience the least inductive effect. It retains more electron density.
- **C2**: This carbon is in the middle; it experiences some inductive effect from fluorine but less than C3.
- **C3**: This carbon is directly attached to fluorine, so it loses electron density due to the -I effect. It will have less electron density compared to C1 and C2.

5. **Conclusion**:
Since C1 is the farthest from the electronegative fluorine and experiences the least withdrawal of electron density, it retains the most electron density. Therefore, the carbon with the most electron density in the molecule is **C1**.

### Final Answer:
The carbon with the most electron density is **C1**.