In which of the following bond angle is maximum ?

Options

A. `NH_(3)`
B. `PCl_(3)`
C. `BCl_(3)`
D. `PCl_(6)^(-)`

Answer

To determine which of the given compounds has the maximum bond angle, we will analyze each compound one by one based on their molecular geometry and hybridization.

### Step 1: Analyze NH3 (Ammonia)
1. **Valence Electrons**: Nitrogen (N) has 5 valence electrons and each hydrogen (H) contributes 1 electron. Thus, NH3 has a total of 5 + 3 = 8 valence electrons.
2. **Hybridization**: NH3 undergoes sp³ hybridization.
3. **Molecular Geometry**: The molecular shape is trigonal pyramidal due to one lone pair on nitrogen.
4. **Bond Angle**: The ideal bond angle for sp³ hybridization is 109.5°, but due to the presence of a lone pair, the bond angle is reduced to approximately 107°.

### Step 2: Analyze PCl3 (Phosphorus Trichloride)
1. **Valence Electrons**: Phosphorus (P) has 5 valence electrons and each chlorine (Cl) contributes 7 electrons. Thus, PCl3 has a total of 5 + 3*7 = 26 valence electrons.
2. **Hybridization**: PCl3 also undergoes sp³ hybridization.
3. **Molecular Geometry**: The molecular shape is trigonal pyramidal due to one lone pair on phosphorus.
4. **Bond Angle**: Similar to NH3, the bond angle is approximately 107°.

### Step 3: Analyze BCl3 (Boron Trichloride)
1. **Valence Electrons**: Boron (B) has 3 valence electrons and each chlorine (Cl) contributes 7 electrons. Thus, BCl3 has a total of 3 + 3*7 = 24 valence electrons.
2. **Hybridization**: BCl3 undergoes sp² hybridization.
3. **Molecular Geometry**: The molecular shape is trigonal planar.
4. **Bond Angle**: The bond angle for sp² hybridization is 120°.

### Step 4: Analyze PCl6- (Phosphorus Hexachloride)
1. **Valence Electrons**: Phosphorus (P) has 5 valence electrons and each chlorine (Cl) contributes 7 electrons. Thus, PCl6- has a total of 5 + 6*7 + 1 (for the negative charge) = 43 valence electrons.
2. **Hybridization**: PCl6- undergoes sp³d² hybridization.
3. **Molecular Geometry**: The molecular shape is octahedral.
4. **Bond Angle**: In an octahedral geometry, the bond angles are 90° between adjacent bonds and 180° between opposite bonds.

### Conclusion
After analyzing all the compounds:
- NH3 has a bond angle of approximately 107°.
- PCl3 has a bond angle of approximately 107°.
- BCl3 has a bond angle of 120°.
- PCl6- has bond angles of 90° and 180°.

**Maximum Bond Angle**: The maximum bond angle among these compounds is found in PCl6-, which can be 180°.

### Final Answer
The compound with the maximum bond angle is **PCl6-** (option D).

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