Among the following which islare interstitial hydride ?

Options

A. `LaH_(3)`
B. `CaH_(2)`
C. `NaH`
D. HF

Answer

To determine which of the given compounds is an interstitial hydride, we need to understand the characteristics of interstitial hydrides and the groups of elements that can form them.

### Step-by-Step Solution:

1. **Define Interstitial Hydrides**:
Interstitial hydrides are compounds formed when hydrogen occupies the interstitial sites in a metal lattice. These hydrides are typically formed by transition metals (d-block) and some f-block elements.

2. **Identify the Groups**:
According to the information, interstitial hydrides are primarily formed by d-block and f-block elements, with exceptions for groups 7, 8, and 9 of the d-block. The only exception in the d-block is chromium (Cr), which can form a hydride (CrH).

3. **Analyze the Options**:
- **Option 1: LAH3**:
- L.A. refers to a lanthanide element, which is part of the f-block. Since f-block elements can form interstitial hydrides, this is a potential candidate.
- **Option 2: CaS2**:
- Calcium (Ca) is an s-block element. S-block elements do not form interstitial hydrides. Therefore, this option is incorrect.
- **Option 3: NAH**:
- Sodium (Na) is also an s-block element. Like calcium, it does not form interstitial hydrides. Thus, this option is incorrect as well.
- **Option 4: HF**:
- HF consists of hydrogen and fluorine. Fluorine is a p-block element, and p-block elements do not form interstitial hydrides. Therefore, this option is incorrect.

4. **Conclusion**:
Based on the analysis, the only compound that qualifies as an interstitial hydride is **LAH3**.

### Final Answer:
The interstitial hydride among the given options is **LAH3**.

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