Which of the following statement is not correct ?
(a) `[Ni(H_(2)O)_(6)]^(2+)` and `[Ni(NH_(3))_(6)]^(2+)` have same value of CFSE
( b) `[Ni(H_(2)O)_(6)]^(2+)` and `[Ni(NH_(3))_(6)]^(2+)` have same value of magnetic moment

Options

A. Only a
B. Only b
C. Both a and b
D. None of these

Explanation

To determine which of the statements is not correct regarding the coordination compounds `[Ni(H₂O)₆]²⁺` and `[Ni(NH₃)₆]²⁺`, we need to analyze both statements provided in the question.

### Step 1: Understanding Crystal Field Stabilization Energy (CFSE)

**Statement (a):** `[Ni(H₂O)₆]²⁺` and `[Ni(NH₃)₆]²⁺` have the same value of CFSE.

- Nickel in both complexes has a +2 oxidation state.
- `[Ni(H₂O)₆]²⁺` has water as a ligand, while `[Ni(NH₃)₆]²⁺` has ammonia as a ligand.
- Water is a weaker field ligand compared to ammonia, which is a stronger field ligand.
- As a result, ammonia will cause a greater splitting of the d-orbitals compared to water.
- Therefore, the CFSE values for these two complexes will not be the same.

**Conclusion for Statement (a):** This statement is **not correct**.

### Step 2: Understanding Magnetic Moment

**Statement (b):** `[Ni(H₂O)₆]²⁺` and `[Ni(NH₃)₆]²⁺` have the same value of magnetic moment.

- The magnetic moment is determined by the number of unpaired electrons in the d-orbitals.
- In `[Ni(H₂O)₆]²⁺`, the complex is typically high-spin due to the weaker field strength of water, leading to two unpaired electrons.
- In `[Ni(NH₃)₆]²⁺`, ammonia being a stronger field ligand, leads to a low-spin configuration, which typically results in no unpaired electrons.
- Therefore, the magnetic moments of these two complexes will be different.

**Conclusion for Statement (b):** This statement is also **not correct**.

### Final Conclusion

Since both statements (a) and (b) are not correct, the answer to the question is that both statements are incorrect.

### Answer: Both (a) and (b) are not correct.

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