Which of the following is interstitial hydride?

Options

A. `CaH_(2)`
B. CuH
C. `PH_(3)`
D. NaH

Answer

To determine which of the following options is an interstitial hydride, we need to understand the characteristics of interstitial hydrides and the types of elements that form them.

### Step-by-Step Solution:

1. **Understand the Types of Hydrides**:
- Hydrides can be classified into three main types: covalent, ionic, and interstitial (metallic).
- **Covalent Hydrides**: Typically formed by non-metals (P-block elements) and some exceptions in S-block (like Beryllium and Magnesium).
- **Ionic Hydrides**: Formed by elements with a significant difference in electronegativity, usually S-block elements.
- **Interstitial Hydrides**: Formed by D-block and some F-block elements, where hydrogen occupies the interstitial sites in the metal lattice.

2. **Identify the Elements in the Options**:
- Let's consider the options provided in the question (though not specified here, we will assume common examples like Calcium, Copper, Phosphorus, and Sodium Hydride).
- **Calcium (Ca)**: An S-block element, forms ionic hydrides (e.g., CaH2).
- **Copper (Cu)**: A D-block element, can form interstitial hydrides (e.g., CuH).
- **Phosphorus (P)**: A non-metal, forms covalent hydrides (e.g., PH3).
- **Sodium Hydride (NaH)**: An S-block element, forms ionic hydrides.

3. **Determine the Interstitial Hydride**:
- From the analysis, we see that:
- Calcium forms ionic hydrides.
- Copper forms interstitial hydrides.
- Phosphorus forms covalent hydrides.
- Sodium forms ionic hydrides.
- Therefore, the only interstitial hydride among the options is **Copper Hydride (CuH)**.

### Final Answer:
The interstitial hydride is **Copper Hydride (CuH)**.

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