The bond angle H-X-H is the greatest in teh compound :

Options

A. `CH_(4)`
B. `NH_(3)`
C. `H_(2)O`
D. `PH_(3)`

Explanation

To determine which compound has the greatest bond angle H-X-H, we will analyze the bond angles in various compounds containing hydrogen and other elements. The compounds we will consider are CH4 (methane), NH3 (ammonia), H2O (water), and PH3 (phosphine).

### Step-by-Step Solution:

1. **Identify the Compounds**: We will examine the following compounds:
- CH4 (methane)
- NH3 (ammonia)
- H2O (water)
- PH3 (phosphine)

2. **Calculate Hybridization and Bond Angles**:
- **For CH4**:
- Valence electrons: Carbon (C) has 4, and there are 4 hydrogens (H).
- Total = 4 (C) + 4 (H) = 8
- Hybridization = \( \frac{1}{2} \times (8) = 4 \) → sp³
- Structure: Tetrahedral
- Bond angle: 109.5°

- **For NH3**:
- Valence electrons: Nitrogen (N) has 5, and there are 3 hydrogens (H).
- Total = 5 (N) + 3 (H) = 8
- Hybridization = \( \frac{1}{2} \times (8) = 4 \) → sp³
- Structure: Tetrahedral with one lone pair
- Bond angle: 107°

- **For H2O**:
- Valence electrons: Oxygen (O) has 6, and there are 2 hydrogens (H).
- Total = 6 (O) + 2 (H) = 8
- Hybridization = \( \frac{1}{2} \times (8) = 4 \) → sp³
- Structure: Bent (due to 2 lone pairs)
- Bond angle: 104.5°

- **For PH3**:
- Valence electrons: Phosphorus (P) has 5, and there are 3 hydrogens (H).
- Total = 5 (P) + 3 (H) = 8
- Hybridization = \( \frac{1}{2} \times (8) = 4 \) → sp³
- Structure: Trigonal pyramidal (due to one lone pair)
- Bond angle: 93.5° (approximately)

3. **Compare the Bond Angles**:
- CH4: 109.5°
- NH3: 107°
- H2O: 104.5°
- PH3: 93.5°

4. **Conclusion**: The bond angle H-X-H is greatest in CH4 (methane), which has a bond angle of 109.5°.

### Final Answer:
The bond angle H-X-H is the greatest in the compound CH4 (methane).

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