Which element from electron rich hydride ?

Options

A. C
B. O
C. B
D. Al

Answer

To determine which element forms an electron-rich hydride, we need to understand what an electron-rich hydride is and identify the relevant groups in the periodic table.

### Step-by-Step Solution:

1. **Understanding Electron-Rich Hydrides**:
- Electron-rich hydrides are those in which the central atom has more electrons than required to complete its octet. This typically occurs in elements from groups 15 to 17 of the periodic table.

2. **Identifying the Groups**:
- Group 15 elements include Nitrogen (N), Phosphorus (P), Arsenic (As), etc.
- Group 16 elements include Oxygen (O), Sulfur (S), Selenium (Se), etc.
- Group 17 elements include Fluorine (F), Chlorine (Cl), Bromine (Br), etc.

3. **Analyzing the Options**:
- **Option 1: Carbon (C)** - Carbon belongs to Group 14. It does not form electron-rich hydrides. **(Incorrect)**
- **Option 2: Oxygen (O)** - Oxygen belongs to Group 16. It can form electron-rich hydrides, such as water (H2O) where it has two lone pairs of electrons. **(Correct)**
- **Option 3: Boron (B)** - Boron belongs to Group 13. It does not form electron-rich hydrides. **(Incorrect)**
- **Option 4: Aluminum (Al)** - Aluminum also belongs to Group 13. It does not form electron-rich hydrides. **(Incorrect)**

4. **Conclusion**:
- The only element from the given options that forms an electron-rich hydride is **Oxygen (O)**.

### Final Answer:
The element that forms an electron-rich hydride is **Oxygen (O)**.