The s-block hydride with covalent polymeric structure are

Options

A. `CaH_(2)`
B. `BeH_(2)`
C. `NaH`
D. `BaH_(2)`

Explanation

To determine the s-block hydride with a covalent polymeric structure, we will analyze the properties of the hydrides of the s-block elements, particularly focusing on beryllium hydride (BeH₂).

### Step-by-Step Solution:

1. **Identify the s-block elements**:
- The s-block elements include Group 1 (alkali metals) and Group 2 (alkaline earth metals) of the periodic table.

2. **Consider the hydrides of s-block elements**:
- The hydrides of these elements include:
- Alkali metal hydrides: LiH, NaH, KH, etc.
- Alkaline earth metal hydrides: BeH₂, MgH₂, CaH₂, etc.

3. **Analyze the nature of the hydrides**:
- Alkali metal hydrides (e.g., LiH, NaH) are ionic in nature due to the large size and low electronegativity of alkali metals.
- Alkaline earth metal hydrides (e.g., BeH₂, MgH₂) can exhibit covalent characteristics, especially beryllium hydride.

4. **Focus on Beryllium Hydride (BeH₂)**:
- Beryllium is a small atom with a high electronegativity and high ionization energy compared to other alkaline earth metals.
- Due to these properties, BeH₂ does not form ionic bonds like other alkaline earth metal hydrides; instead, it forms covalent bonds.

5. **Covalent Polymeric Structure of BeH₂**:
- Beryllium hydride exists in a polymeric form where the Be-H bonds create a network structure.
- The structure can be represented as chains of BeH units, indicating its polymeric nature.

6. **Conclusion**:
- Therefore, the s-block hydride with a covalent polymeric structure is **Beryllium Hydride (BeH₂)**.

### Final Answer:
The s-block hydride with a covalent polymeric structure is **Beryllium Hydride (BeH₂)**.

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