Consider the molecules `CH_(4),NH_(3)` and `H_(2)O` which of the given statement is false ?

Options

A. The H - C - H bond angle in `CH_(4)` is larger than the H - N - H bond angle in `NH_(3)`
B. The H - C - H bond angle in `CH_(4)`, the H - N - H bond angle in `NH_(3)` and the H - O - H bond angle in `H_(2) O` are all greater than `90^(@)`
C. The H - O - H bond angle in `H_(2)`O is larger than the H - C - H bond angle in `CH_(4)`
D. The H - O - H bond angle in `H_(2)`O is smaller than the H - N - H bond angle in `NH_(3)`

Answer

To solve the problem, we need to analyze the bond angles in the molecules CH₄ (methane), NH₃ (ammonia), and H₂O (water). We will evaluate each statement provided and determine which one is false.

### Step-by-Step Solution:

1. **Identify the Structures and Bond Angles:**
- **Methane (CH₄):**
- Carbon (C) has 4 valence electrons and forms 4 bonds with hydrogen (H).
- The molecular geometry is tetrahedral.
- The bond angle (H-C-H) is approximately **109.5 degrees**.

- **Ammonia (NH₃):**
- Nitrogen (N) has 5 valence electrons and forms 3 bonds with hydrogen.
- There is 1 lone pair on nitrogen.
- The molecular geometry is trigonal pyramidal.
- The bond angle (H-N-H) is approximately **107 degrees** (less than 109.5 degrees due to lone pair-bond pair repulsion).

- **Water (H₂O):**
- Oxygen (O) has 6 valence electrons and forms 2 bonds with hydrogen.
- There are 2 lone pairs on oxygen.
- The molecular geometry is bent.
- The bond angle (H-O-H) is approximately **104.5 degrees** (even smaller due to increased lone pair-bond pair repulsion).

2. **Evaluate Each Statement:**
- **Statement 1:** "HCH bond angle in methane is larger than the HNH bond angle in ammonia."
- True (109.5° > 107°).

- **Statement 2:** "HCH bond angle in methane, the HNH bond angle in ammonia, and the HOH bond angle in water, are all greater than 90 degrees."
- True (all angles are greater than 90°).

- **Statement 3:** "The HOH bond angle in water is larger than the HCH bond angle in methane."
- False (104.5° < 109.5°).

- **Statement 4:** "HOH bond angle in water is smaller than the HNH bond angle in ammonia."
- True (104.5° < 107°).

3. **Conclusion:**
- The false statement among the given options is **Statement 3**: "The HOH bond angle in water is larger than the HCH bond angle in methane."

### Final Answer:
The false statement is **Statement 3**.

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