Which of the following configuration is not possible ?

Options

A. `2p^(2)`
B. `3f^(2)`
C. `3d^(5)`
D. `4p^(6)`

Answer

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

### Step-by-Step Solution:

1. **Understanding Electron Configurations**:
- Electron configurations are written in the form of subshells (s, p, d, f) along with their respective principal quantum numbers (n).
- Each subshell can hold a specific number of electrons:
- s subshell can hold a maximum of 2 electrons.
- p subshell can hold a maximum of 6 electrons.
- d subshell can hold a maximum of 10 electrons.
- f subshell can hold a maximum of 14 electrons.

2. **Analyzing Each Option**:
- **Option 1: 2P2**
- The 'P' subshell starts from the second energy level (n=2).
- Therefore, 2P2 is a valid configuration as it indicates 2 electrons in the 2p subshell.

- **Option 2: 3F2**
- The 'F' subshell starts from the fourth energy level (n=4).
- Therefore, 3F2 is not a valid configuration because the F subshell cannot exist in the third energy level (n=3).

- **Option 3: 3D5**
- The 'D' subshell starts from the third energy level (n=3).
- Therefore, 3D5 is a valid configuration as it indicates 5 electrons in the 3d subshell.

- **Option 4: 4P6**
- The 'P' subshell starts from the second energy level (n=2).
- Therefore, 4P6 is a valid configuration as it indicates 6 electrons in the 4p subshell.

3. **Conclusion**:
- Based on the analysis, the only configuration that is not possible is **3F2** because the F subshell does not exist in the third energy level.

### Final Answer:
The configuration that is not possible is **3F2**.