Which of the following statements is incorrect?

Options

A. In ferrocyanide ion, the effective atomic number is 36
B. Ferricyanide ion is more stable than ferrocyanide ion
C. `[Cr(H_(2)O)_(6)]^(3+) and [Cr(NH_(3))_(6)]^(3+)" have "sp^(3)d^(2) and d^(2)sp^(3)` and have and hybridization respectively.
D. In `[Co(H_(2)O)_(6)]^(2+)` the hybridization `sp^(3)d^(2)` is while in `[Co(NH_(3))_(6)]^(3+)` the hybridization is `d^(2)sp^(3)`

Explanation

To determine which statement is incorrect regarding the effective atomic number (EAN) and hybridization of complexes, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Effective Atomic Number (EAN):**
- The EAN is calculated using the formula:
\[ \text{EAN} = Z - n + 2m \]
where \( Z \) is the atomic number of the central metal atom, \( n \) is the oxidation state of the metal, and \( m \) is the number of ligands.

2. **Calculate EAN for Ferrocyanide:**
- For Ferrocyanide, the formula is \( \text{Fe(CN)}_6^{4-} \).
- The oxidation state of Fe in this complex can be calculated as follows:
- Each cyanide (CN) has a charge of -1, and there are 6 cyanides, giving a total charge of -6.
- To balance this with the overall charge of -4, Fe must have a charge of +2.
- Therefore, the oxidation state of Fe is +2.

3. **Determine Atomic Number of Iron:**
- The atomic number of iron (Fe) is 26.

4. **Substituting Values into EAN Formula:**
- Now substituting into the EAN formula:
\[ \text{EAN} = 26 - 2 + 2 \times 6 \]
\[ \text{EAN} = 26 - 2 + 12 = 36 \]
- This confirms that the EAN for Ferrocyanide is indeed 36.

5. **Hybridization of Complexes:**
- For \( \text{Cr(H}_2\text{O)}_6^{3+} \) and \( \text{Cr(NH}_3)_6^{3+} \):
- Both complexes have a +3 charge on chromium.
- The hybridization for \( \text{Cr(H}_2\text{O)}_6^{3+} \) is \( d^2sp^3 \) since water is a weak field ligand and does not cause pairing.
- The hybridization for \( \text{Cr(NH}_3)_6^{3+} \) is \( d^2sp^3 \) as well because ammonia is a strong field ligand and can cause pairing.

6. **Hybridization of Cobalt Complexes:**
- For \( \text{Co(H}_2\text{O)}_6^{2+} \):
- Cobalt has an atomic number of 27, and in the +2 oxidation state, it has 7 d-electrons.
- The hybridization is \( sp^3d^2 \) because water is a weak field ligand.
- For \( \text{Co(NH}_3)_6^{3+} \):
- In the +3 oxidation state, cobalt has 6 d-electrons.
- The hybridization is \( d^2sp^3 \) due to the strong field nature of ammonia.

7. **Identifying the Incorrect Statement:**
- The statements regarding the EAN and hybridization of the complexes were analyzed.
- The statement that claims \( \text{Co(H}_2\text{O)}_6^{2+} \) has \( sp^3d^2 \) hybridization while \( \text{Co(NH}_3)_6^{3+} \) has \( d^2sp^3 \) hybridization is correct.
- Therefore, the incorrect statement must be identified from the options provided, which is likely related to the hybridization or EAN values.

### Conclusion:
The incorrect statement is identified as **C** based on the analysis of EAN and hybridization.