Which of the following is violating hund's rule :-

Options

A.
B.
C.
D. all

Answer

To determine which of the following configurations violates Hund's rule, we need to understand the principle behind Hund's rule itself.

### Step-by-Step Solution:

1. **Understanding Hund's Rule**:
- Hund's rule states that for degenerate orbitals (orbitals of the same energy level, such as p, d, and f orbitals), electrons will fill each orbital singly before any orbital is doubly occupied. Additionally, all singly occupied orbitals will have electrons with the same spin.

2. **Identifying Electron Configurations**:
- We need to analyze the given electron configurations to see if they adhere to Hund's rule. The configurations should show how electrons are distributed across the orbitals.

3. **Checking Each Configuration**:
- For each configuration, check if:
- Each orbital in the subshell has one electron before any orbital gets a second electron.
- If there are two electrons in an orbital, they must have opposite spins.

4. **Example Configurations**:
- Let's consider some hypothetical configurations:
- Configuration A: 1 electron in each of the three p orbitals (2px, 2py, 2pz) → This follows Hund's rule.
- Configuration B: 2 electrons in 2px with opposite spins, and 1 electron in 2py and 2pz → This follows Hund's rule.
- Configuration C: 1 electron in 2px, 1 in 2py, and 2 in 2pz with opposite spins → This violates Hund's rule because 2pz is filled before 2py is singly occupied.
- Configuration D: 1 electron in each of the three p orbitals with the same spin → This violates Hund's rule because all singly occupied orbitals must have the same spin.

5. **Conclusion**:
- After analyzing the configurations, any configuration that has paired electrons in an orbital before all orbitals have at least one electron or has all electrons in singly occupied orbitals with the same spin violates Hund's rule.