Which of the folliwing complex is inner orbital as well as low spin complex? .

Options

A. `[Cr(H_(2)O)_(6)]^(3+)`
B. `[Fe(CN)_(6)]^(3-)`
C. `[Cu(CN)_(4)]^(3-)`
D. `[Mn(NH_(3))_(6)]^(2+)`

Explanation

To determine which of the following complexes is both an inner orbital and a low spin complex, we need to analyze the given complexes based on their metal oxidation states, electron configurations, and the nature of the ligands.

### Step-by-Step Solution:

1. **Identify the complexes**: We need to analyze the following complexes:
- Cr(H2O)6^3+
- Fe(CN)6^3-
- Cu(CN)4^3-
- Mn(NH3)6^2+

2. **Determine the oxidation states and electron configurations**:
- **Cr(H2O)6^3+**: Chromium (Cr) has an atomic number of 24. In the +3 oxidation state, its electron configuration is [Ar] 3d^3. H2O is a weak field ligand, leading to high spin.
- **Fe(CN)6^3-**: Iron (Fe) has an atomic number of 26. In the +3 oxidation state, its electron configuration is [Ar] 3d^5. CN^- is a strong field ligand, leading to pairing of electrons, resulting in low spin.
- **Cu(CN)4^3-**: Copper (Cu) has an atomic number of 29. In the +1 oxidation state, its electron configuration is [Ar] 3d^10. CN^- is a strong field ligand, but all electrons are paired, leading to no inner orbital hybridization.
- **Mn(NH3)6^2+**: Manganese (Mn) has an atomic number of 25. In the +2 oxidation state, its electron configuration is [Ar] 3d^5. NH3 is a moderate field ligand, which can lead to low spin if pairing occurs.

3. **Analyze hybridization**:
- **Cr(H2O)6^3+**: Coordination number is 6, hybridization is d^2sp^3 (inner orbital), but it is high spin.
- **Fe(CN)6^3-**: Coordination number is 6, hybridization is d^2sp^3 (inner orbital), and it is low spin.
- **Cu(CN)4^3-**: Coordination number is 4, hybridization is sp^3 (outer orbital), and it is not low spin.
- **Mn(NH3)6^2+**: Coordination number is 6, hybridization is d^2sp^3 (inner orbital), and it can be low spin depending on the ligand strength.

4. **Conclusion**: The complex that is both an inner orbital and a low spin complex is **Fe(CN)6^3-**.

### Final Answer:
The complex that is both an inner orbital and a low spin complex is **Fe(CN)6^3-**.