Which of the following is not a best representation of the H-bond?

Options

A.
B.
C.
D. None

Explanation

To determine which representation is not the best representation of the hydrogen bond, we will analyze the options provided in the question.

### Step-by-Step Solution:

1. **Understanding Hydrogen Bonding**:
- Hydrogen bonding occurs when a hydrogen atom covalently bonded to a highly electronegative atom (like oxygen or nitrogen) interacts with another electronegative atom.
- There are two types of hydrogen bonding:
- **Intermolecular Hydrogen Bonding**: Occurs between different molecules.
- **Intramolecular Hydrogen Bonding**: Occurs within the same molecule.

2. **Analyzing the Options**:
- **Option A**: This representation shows water (H₂O) with acidic hydrogen bonding with another electronegative atom. Water can act as both an acid (donating H⁺) and a base (donating lone pairs). This is a correct representation of hydrogen bonding.
- **Option B**: This representation indicates intramolecular hydrogen bonding, where a hydrogen atom is bonded to an electronegative atom (like oxygen) within the same molecule. This is also a correct representation of hydrogen bonding.
- **Option C**: In this option, it suggests that OH (from water) is donating its lone pair to ammonia. However, water is not a good base that can donate its lone pair effectively in this context. Ammonia is a good base and can donate its lone pair, but the interaction described here does not represent a proper hydrogen bond.

3. **Conclusion**:
- Based on the analysis, **Option C** is not the best representation of a hydrogen bond, as it incorrectly describes the interaction between water and ammonia.

### Final Answer:
**Option C** is not the best representation of the hydrogen bond.