The most stained cycloalkane is :

Options

A. Cyclopropane
B. Cyclobutane
C. Cyclopentane
D. Cyclohexane

Explanation

To determine which cycloalkane has the most strain, we can analyze the structures and bond angles of the different cycloalkanes: cyclopropane, cyclobutane, cyclopentane, and cyclohexane.

### Step-by-Step Solution:

1. **Understanding Baeyer's Strain Theory**:
- Baeyer's strain theory helps us understand the stability of cyclic compounds by examining angle strain. Angle strain occurs when the bond angles in a molecule deviate from the ideal tetrahedral angle of 109.5°.

2. **Identifying the Desired Bond Angles**:
- For cycloalkanes, the ideal bond angle is approximately 109.5° (tetrahedral geometry).

3. **Calculating Actual Bond Angles**:
- **Cyclopropane**: The actual bond angle is 60° (triangle).
- **Cyclobutane**: The actual bond angle is approximately 90° (square).
- **Cyclopentane**: The actual bond angle is approximately 108° (pentagon).
- **Cyclohexane**: The actual bond angle is approximately 120° (hexagon).

4. **Calculating Angle Strain**:
- Angle strain is calculated as the difference between the desired bond angle (109.5°) and the actual bond angle.
- **Cyclopropane**: Angle strain = 109.5° - 60° = 49.5°
- **Cyclobutane**: Angle strain = 109.5° - 90° = 19.5°
- **Cyclopentane**: Angle strain = 109.5° - 108° = 1.5°
- **Cyclohexane**: Angle strain = 109.5° - 120° = -10.5° (no strain, actually more stable)

5. **Comparing Angle Strains**:
- From the calculations, cyclopropane has the highest angle strain of 49.5°, followed by cyclobutane with 19.5°, cyclopentane with 1.5°, and cyclohexane which has no significant angle strain.

6. **Conclusion**:
- Therefore, the cycloalkane with the most strain is **cyclopropane**.

### Final Answer:
The most strained cycloalkane is **cyclopropane**.

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