`Cr^(+3)` in aqueous medium form green coloured complex with`NH_(3)` ligand. How many ligand associated

Options

A. 3
B. 4
C. 5
D. 6

Explanation

To determine how many ligands are associated with the chromium ion \( \text{Cr}^{3+} \) in the presence of the ammonia (\( \text{NH}_3 \)) ligand, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the oxidation state of chromium**:
- In the complex, chromium is in the +3 oxidation state, denoted as \( \text{Cr}^{3+} \).

2. **Understand the coordination in aqueous medium**:
- In aqueous solution, chromium typically forms a hexaaqua complex, represented as \( [\text{Cr(H}_2\text{O)}_6]^{3+} \). This indicates that chromium is surrounded by six water molecules.

3. **Substitution of ligands**:
- When ammonia (\( \text{NH}_3 \)) is introduced, it can replace the water molecules in the coordination sphere. Ammonia is a neutral ligand and can coordinate to the metal ion.

4. **Formation of the complex**:
- The complex formed is \( [\text{Cr(NH}_3)_6]^{3+} \). This indicates that all six coordination sites of chromium are occupied by ammonia ligands.

5. **Determine the number of ligands**:
- Since the complex \( [\text{Cr(NH}_3)_6]^{3+} \) contains six ammonia ligands, we conclude that the number of ligands associated with \( \text{Cr}^{3+} \) is 6.

### Final Answer:
The number of ligands associated with \( \text{Cr}^{3+} \) is **6**.

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