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

Options

A.
B.
C.
D. None

Explanation

To determine which of the options is not the best representation of a hydrogen bond, we need to understand the nature of hydrogen bonding and the role of electronegative atoms.

### Step-by-Step Solution:

1. **Understanding Hydrogen Bonding**:
- Hydrogen bonds are weak attractions that occur between a hydrogen atom covalently bonded to an electronegative atom (like nitrogen, oxygen, or fluorine) and another electronegative atom.

2. **Identifying Electronegativity**:
- The strength of hydrogen bonds depends on the electronegativity of the atoms involved. The more electronegative the atom, the stronger the hydrogen bond it can form. The common electronegative atoms involved in hydrogen bonding are nitrogen (N), oxygen (O), and fluorine (F).

3. **Analyzing the Options**:
- We need to evaluate each option provided in the question to see if it correctly represents a hydrogen bond.
- For example, if an option shows hydrogen bonding between hydrogen and chlorine (Cl), we need to consider that chlorine is less electronegative than nitrogen, oxygen, and fluorine, making it a weaker hydrogen bond.

4. **Evaluating Specific Cases**:
- If an option shows hydrogen bonding between water (H2O) and nitrogen (NH3), we need to analyze the interaction. Oxygen in water is more electronegative than nitrogen, which means it would hold onto its lone pair more tightly and would not effectively donate it to hydrogen in NH3.

5. **Conclusion**:
- After evaluating the options, we find that the representation of hydrogen bonding between H2O and NH3 (where oxygen donates a lone pair to hydrogen) is incorrect. Instead, it should be the nitrogen in NH3 donating its lone pair to the hydrogen in H2O. Therefore, this option does not represent a valid hydrogen bond.

### Final Answer:
The option that is not the best representation of a hydrogen bond is the one showing hydrogen bonding between H2O and NH3 (where oxygen is incorrectly represented as donating a lone pair to hydrogen).

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