Which of the followingg elements does not form hydride by direct heating with dihydrogen?

Options

A. `Be`
B. Mg
C. Sr
D. Ba

Explanation

To determine which of the following elements does not form a hydride by direct heating with dihydrogen, we will analyze the elements given: beryllium, magnesium, strontium, and barium.

### Step-by-Step Solution:

1. **Identify the Elements**: The elements in question are beryllium (Be), magnesium (Mg), strontium (Sr), and barium (Ba). These elements belong to the alkaline earth metals group (Group 2 of the periodic table).

2. **Understand Hydride Formation**: Hydrides are compounds formed when hydrogen combines with another element. For alkaline earth metals, the formation of hydrides typically occurs through direct heating with dihydrogen (H2).

3. **Analyze Each Element**:
- **Beryllium (Be)**: Beryllium is unique among the alkaline earth metals due to its small atomic size and high ionization potential. It does not readily form BeH2 by direct heating with dihydrogen.
- **Magnesium (Mg)**: Magnesium can form magnesium hydride (MgH2) when heated with dihydrogen.
- **Strontium (Sr)**: Strontium can also form strontium hydride (SrH2) through direct heating with dihydrogen.
- **Barium (Ba)**: Barium can form barium hydride (BaH2) when heated with dihydrogen.

4. **Conclusion**: Based on the analysis, beryllium is the only element among the given options that does not form a hydride by direct heating with dihydrogen.

### Final Answer:
**Beryllium (Be)** does not form a hydride by direct heating with dihydrogen.