Which of the following molecules does not show hydrogen bonding?

Options

A. HF
B. `H_2O`
C. `NH_3`
D. `H_2S`

Answer

To determine which of the following molecules does not show hydrogen bonding, we need to understand the conditions necessary for hydrogen bonding to occur.

### Step-by-Step Solution:

1. **Understanding Hydrogen Bonding**:
- Hydrogen bonding occurs when hydrogen is covalently bonded to a highly electronegative atom, such as fluorine (F), oxygen (O), or nitrogen (N). This creates a significant dipole, where hydrogen carries a partial positive charge and the electronegative atom carries a partial negative charge.

2. **Identifying Electronegativity**:
- The key to identifying whether a molecule can exhibit hydrogen bonding is to look for the presence of highly electronegative atoms bonded to hydrogen.

3. **Analyzing the Given Options**:
- **Option 1: HF (Hydrogen Fluoride)**:
- HF has hydrogen bonded to fluorine, which is highly electronegative. Therefore, HF exhibits hydrogen bonding.
- **Option 2: H2O (Water)**:
- Water has hydrogen atoms bonded to oxygen, another highly electronegative atom. Thus, water also exhibits hydrogen bonding.
- **Option 3: NH3 (Ammonia)**:
- Ammonia has hydrogen atoms bonded to nitrogen, which is also electronegative. Therefore, ammonia exhibits hydrogen bonding.
- **Option 4: H2S (Hydrogen Sulfide)**:
- In H2S, hydrogen is bonded to sulfur, which is not as electronegative as fluorine, oxygen, or nitrogen. Consequently, H2S does not exhibit significant hydrogen bonding.

4. **Conclusion**:
- Based on the analysis, the molecule that does not show hydrogen bonding is **H2S**.

### Final Answer:
The correct answer is **Option 4: H2S**.