Which of the following molecule froms linear polymeric structure due to H-bonding ?

Options

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

Explanation

To determine which molecule forms a linear polymeric structure due to hydrogen bonding, we need to analyze the options provided based on the ability of certain atoms to form hydrogen bonds. Here's a step-by-step solution:

### Step 1: Understand Hydrogen Bonding
Hydrogen bonding occurs when hydrogen is bonded to highly electronegative atoms such as fluorine (F), oxygen (O), or nitrogen (N). These atoms have a strong tendency to attract electrons, which allows them to form hydrogen bonds with other molecules.

**Hint:** Remember that only F, O, and N can form strong hydrogen bonds due to their high electronegativity.

### Step 2: Analyze the Given Molecules
We will evaluate each molecule to see if it can form a linear polymeric structure through hydrogen bonding.

1. **HCl (Hydrochloric Acid)**:
- HCl does not form hydrogen bonds effectively because chlorine (Cl) is larger and less electronegative compared to F, O, and N. Therefore, HCl cannot form a polymeric structure.

**Hint:** Consider the size and electronegativity of the atoms involved.

2. **HF (Hydrofluoric Acid)**:
- HF can form strong hydrogen bonds due to the presence of fluorine. The structure of HF allows for linear arrangements of molecules through hydrogen bonding, resulting in a linear polymeric structure.

**Hint:** Look for strong hydrogen bonds that can lead to linear arrangements.

3. **NH3 (Ammonia)**:
- NH3 can form hydrogen bonds, but these bonds are relatively weak compared to those in HF. The structure of NH3 does not allow for a linear polymeric arrangement; instead, it tends to form a tetrahedral shape.

**Hint:** Evaluate the strength of hydrogen bonds and the resulting molecular geometry.

4. **H2O (Water)**:
- H2O can form hydrogen bonds and does create a polymeric structure, but it is tetrahedral in nature rather than linear. Thus, it does not fit the criteria for a linear polymeric structure.

**Hint:** Consider the geometry of the polymeric structure formed by the hydrogen bonds.

### Step 3: Conclusion
Based on the analysis:
- **HCl** does not form hydrogen bonds.
- **HF** forms a linear polymeric structure due to strong hydrogen bonding.
- **NH3** does not form a polymeric structure due to weak hydrogen bonds.
- **H2O** forms a tetrahedral polymeric structure, not linear.

Thus, the correct answer is **HF**.

**Final Answer:** HF forms a linear polymeric structure due to hydrogen bonding.