Which of the following order of CFSE is incorrect?

Options

A. `[Co(en)_(3)]^(3+) gt [Co(NH_(3))_(6)]^(3+) gt [Co(H_(2)O)_(6)]^(3+)`
B. `[PtCl_(4)]^(2-) gt [PdCl_(4)]^(2-) gt [NiCl_(4)]^(2-)`
C. `[Ni(DMG)_(2)] lt Ni(en)_(2)]^(2+)`
D. `[Co(o x)_(3)]^(3-) lt [Co(en)_(3)]^(3+)`

Explanation

To determine which order of Crystal Field Stabilization Energy (CFSE) is incorrect, we need to analyze the given ligands and their corresponding strengths, as well as the central metal ions involved. The ligands have different strengths, and the CFSE depends on both the ligand field strength and the geometry of the complexes.

### Step-by-Step Solution:

1. **Identify the Ligands and Their Strengths**:
- Ethylene diamine (en) is a strong field ligand.
- Ammonia (NH3) is a moderate field ligand.
- Water (aqua, H2O) is a weak field ligand.
- DMG (Dimethylglyoxime) is a strong field ligand.
- Oxalato (C2O4) is also a strong field ligand.

2. **Analyze the Given Orders**:
- The first order compares en, NH3, and aqua:
- Correct order: en > NH3 > H2O (stronger to weaker).
- The second order compares platinum, palladium, and nickel:
- As we go down the group, the stability of square planar complexes increases.
- Correct order: Ni < Pd < Pt (increasing stability).
- The third order compares Ni with DMG and en:
- Here, DMG is a stronger ligand than en due to its ring stability.
- Incorrect order: DMG > en (should be reversed).
- The fourth order compares oxalato and en:
- Correct order: en > oxalato (en is a stronger ligand).

3. **Identify the Incorrect Order**:
- The incorrect order is found in the comparison of Ni with DMG and en. The correct relationship is DMG > en, but it was stated incorrectly in the options.

4. **Conclusion**:
- The answer to the question is that the third option, which compares Ni with DMG and en, is the incorrect order of CFSE.

### Final Answer:
The incorrect order of CFSE is in the comparison of Ni, DMG, and en (Option 3).