Which of the following electronic configuration is not possible ?

Options

A. `2p^3`
B. `2d^6`
C. `4s^1`
D. `5f^8`

Answer

To determine which of the given electronic configurations is not possible, we need to analyze each configuration based on the rules of electron filling and the structure of atomic orbitals.

### Step-by-Step Solution:

1. **Understanding Electron Configuration**:
- Electron configurations are represented by the notation of energy levels (n), subshells (s, p, d, f), and the number of electrons in those subshells.

2. **Identifying the Subshells**:
- The subshells available in each principal energy level (n) are:
- n = 1: 1s
- n = 2: 2s, 2p
- n = 3: 3s, 3p, 3d
- n = 4: 4s, 4p, 4d, 4f

3. **Analyzing Each Option**:
- **Option 1: 2p³**: This configuration is possible as the 2p subshell can hold up to 6 electrons.
- **Option 2: 2d⁶**: This configuration is not possible because the d subshell starts from n=3 (3d). Therefore, there is no 2d subshell.
- **Option 3: 4s¹**: This configuration is possible as the 4s subshell can hold up to 2 electrons.
- **Option 4: 5f⁸**: This configuration is possible as the 5f subshell can hold up to 14 electrons.

4. **Conclusion**:
- The only configuration that is not possible is **2d⁶**.

### Final Answer:
The electronic configuration that is not possible is **2d⁶**.

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