In which group of the d-block the electronic configuration is not as expected?

Explanation

To solve the question "In which group of the d-block the electronic configuration is not as expected?", we will analyze the electronic configurations of d-block elements and identify any deviations from the expected configurations.

### Step-by-Step Solution:

1. **Understanding d-block Elements**:
- The d-block elements are transition metals found in groups 3 to 12 of the periodic table. Their general electronic configuration can be expressed as \( [noble \ gas] \ n-1 d^{1-10} \ ns^{0-2} \).

2. **General Electronic Configuration**:
- For d-block elements, the expected electronic configuration is \( [noble \ gas] \ n-1 d^{x} \ ns^{y} \), where \( x \) can range from 1 to 10 and \( y \) can be 0, 1, or 2.

3. **Identifying the Anomaly**:
- In most cases, the electronic configuration follows the Aufbau principle, where electrons fill the lower energy orbitals first. However, there are exceptions.

4. **Focus on Group 6B**:
- Group 6B includes elements like Chromium (Cr) and Molybdenum (Mo). The expected electronic configuration for Chromium would be \( [Ar] \ 3d^4 \ 4s^2 \).

5. **Actual Configuration for Chromium**:
- Instead of following the expected configuration, Chromium has the configuration \( [Ar] \ 3d^5 \ 4s^1 \). This is because having a half-filled d subshell (3d) provides extra stability.

6. **Conclusion**:
- Therefore, the group in the d-block where the electronic configuration is not as expected is **Group 6B**.

### Summary:
The electronic configuration of d-block elements generally follows the expected pattern, but in Group 6B (specifically for elements like Chromium), the configuration deviates to achieve greater stability through half-filled d orbitals.