The correct increasing bond angle among `BF_3 , PF_3 and ClF_3` follows the order

Options

A. `BF_3 lt PF_3 lt ClF_3`
B. `PF_3 lt BF_3 lt ClF_3`
C. `ClF_3 lt PF_3 lt BF_3`
D. `BF_2~~PF_3~~ClF_3`

Explanation

To determine the correct increasing bond angle among BF₃, PF₃, and ClF₃, we will follow these steps:

### Step 1: Determine the Valence Electrons
- **BF₃ (Boron Trifluoride)**: Boron has 3 valence electrons.
- **PF₃ (Phosphorus Trifluoride)**: Phosphorus has 5 valence electrons.
- **ClF₃ (Chlorine Trifluoride)**: Chlorine has 7 valence electrons.

### Step 2: Calculate the Steric Number
The steric number can be calculated using the formula:
\[ \text{Steric Number} = \text{Valence electrons of central atom} + \text{Number of attached monovalent atoms} \]

- **BF₃**:
- Steric Number = 3 (Boron) + 3 (F) = 6
- **PF₃**:
- Steric Number = 5 (Phosphorus) + 3 (F) = 8
- **ClF₃**:
- Steric Number = 7 (Chlorine) + 3 (F) = 10

### Step 3: Determine Hybridization and Geometry
- **BF₃**:
- Steric Number = 3 → Hybridization = sp² → Geometry = Trigonal Planar → Bond Angle ≈ 120°
- **PF₃**:
- Steric Number = 4 → Hybridization = sp³ → Geometry = Tetrahedral → Bond Angle ≈ 109.5° (but with one lone pair, it decreases to ≈ 104°)
- **ClF₃**:
- Steric Number = 5 → Hybridization = sp³d → Geometry = Trigonal Bipyramidal → Bond Angle ≈ 90° and 120° (but with two lone pairs, it decreases to less than 90°)

### Step 4: Compare the Bond Angles
- **BF₃**: 120°
- **PF₃**: 104°
- **ClF₃**: <90°

### Step 5: Order the Bond Angles
The increasing order of bond angles is:
\[ \text{ClF}_3 < \text{PF}_3 < \text{BF}_3 \]

### Final Answer
The correct increasing bond angle among BF₃, PF₃, and ClF₃ follows the order:
\[ \text{ClF}_3 < \text{PF}_3 < \text{BF}_3 \]

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