Which of the following electronic configurations is of transition elements ?

Options

A. `1s^(2)2s^(2)2p^(6)3s^(2)3p^(6) 4s^(2)`
B. `1s^(2)2s^(2)2p^(6)3s^(2)3p^(6)3d^(10)4s^(2)4p^(1)`
C. `1s^(2)2s^(2)2p^(6)3s^(2)3p^(6)3d^(10)4s^(2)4p^(6)`
D. `1s^(2)2s^(2)2p^(6)3s^(2)3p^(6)3d^(2)4s^(2)`

Answer

To determine which electronic configuration corresponds to a transition element, we need to understand the characteristics of transition elements and their electronic configurations.

### Step-by-Step Solution:

1. **Identify Transition Elements**: Transition elements are defined as the d-block elements in the periodic table. These are elements where the last electron enters the d subshell.

2. **Analyze Given Configurations**: Review the electronic configurations provided in the question. We need to look for configurations where the last electron is added to a d subshell (3d, 4d, etc.).

3. **Check Each Configuration**:
- **Configuration A**: If the last electron is in the s subshell (e.g., 4s), it indicates an s-block element.
- **Configuration B**: If the last electron is in the p subshell (e.g., 3p), it indicates a p-block element.
- **Configuration C**: If the configuration is fully filled (e.g., noble gas configuration), it also indicates a p-block element.
- **Configuration D**: If the last electron is in the d subshell (e.g., 3d), it indicates a transition element.

4. **Determine the Correct Configuration**: Among the configurations analyzed, the one where the last electron enters the d subshell is the configuration of a transition element. For example, titanium (Ti) with atomic number 22 has the configuration [Ar] 3d² 4s², where the last electron enters the 3d subshell.

5. **Conclusion**: The configuration corresponding to a transition element is the one where the last electron enters the d subshell.

### Final Answer:
The electronic configuration that corresponds to a transition element is the one where the last electron is added to the d subshell (for example, titanium's configuration).

---