Which of the following given molecules has all the bond angles equal to 120°?

Options

A. `CH_4`
B. `BF_3`
C. `BeCl_2`
D. `PCl_5`

Answer

To determine which of the given molecules has all bond angles equal to 120°, we need to analyze the molecular geometry of each option provided.

### Step-by-Step Solution:

1. **Identify the Molecules**: The molecules we are considering are CH₄, BF₃, BeCl₂, and PCl₅.

2. **Analyze CH₄ (Methane)**:
- **Molecular Geometry**: Tetrahedral
- **Bond Angles**: The bond angles in a tetrahedral structure are approximately 109.5°.
- **Conclusion**: Not all angles are 120°.

3. **Analyze BF₃ (Boron Trifluoride)**:
- **Molecular Geometry**: Trigonal planar
- **Bond Angles**: In a trigonal planar structure, all bond angles are 120°.
- **Conclusion**: All angles are equal to 120°.

4. **Analyze BeCl₂ (Beryllium Dichloride)**:
- **Molecular Geometry**: Linear
- **Bond Angles**: The bond angle in a linear structure is 180°.
- **Conclusion**: Not all angles are 120°.

5. **Analyze PCl₅ (Phosphorus Pentachloride)**:
- **Molecular Geometry**: Trigonal bipyramidal
- **Bond Angles**: In this structure, there are two types of angles: 120° (equatorial) and 90° (axial).
- **Conclusion**: Not all angles are 120°.

6. **Final Conclusion**: The only molecule among the options that has all bond angles equal to 120° is **BF₃**.