STATEMENT-1: `KMnO_(4)` is coloured due to d-d transition .
STATEMENT-2: Colour due to d-d transition will be less intense .
STATEMENT-3: `Fe[Fe(CN)_(6)]` will retain a brown coloured complex after a long time of its formation .

Options

A. TFT
B. FTF
C. TTT
D. TFF

Answer

To analyze the statements provided in the question, we will evaluate each statement one by one, determining their validity based on our understanding of transition metal chemistry, particularly focusing on d-d transitions and the properties of the complexes mentioned.

### Step-by-Step Solution:

**Statement 1: KMnO4 is colored due to d-d transition.**

1. **Identify the central metal ion:** In KMnO4, the central metal ion is manganese (Mn).
2. **Determine the oxidation state of manganese:** In KMnO4, manganese is in the +7 oxidation state.
3. **Check for d-electrons:** Transition metals exhibit color due to d-d transitions, which occur when there are d-electrons available for excitation. However, Mn in the +7 oxidation state has no d-electrons (it has an electron configuration of [Ar] 3d^0).
4. **Conclusion:** Since there are no d-electrons, d-d transitions cannot occur, making this statement **false**.

**Statement 2: Color due to d-d transition will be less intense.**

1. **Understanding d-d transitions:** d-d transitions are typically less intense compared to charge transfer transitions (like metal-to-ligand or ligand-to-metal charge transfers).
2. **Reasoning:** The intensity of color in transition metal complexes is influenced by the nature of the electronic transitions. d-d transitions are generally weaker and therefore less intense than charge transfer transitions.
3. **Conclusion:** This statement is **true**.

**Statement 3: Fe[Fe(CN)6] will retain a brown colored complex after a long time of its formation.**

1. **Identify the complex:** Fe[Fe(CN)6] refers to a complex where iron is coordinated to cyanide ligands.
2. **Color change over time:** Initially, this complex may appear brown, but over time, it can undergo a change due to oxidation states or ligand exchange, leading to a different color (often blue).
3. **Magnetic properties:** The complex can also change from a diamagnetic state to a paramagnetic state, which is often associated with a color change.
4. **Conclusion:** Therefore, this statement is **false** as the complex does not retain its initial brown color.

### Final Evaluation of Statements:
- **Statement 1:** False
- **Statement 2:** True
- **Statement 3:** False

### Overall Conclusion:
The correct answer is that **only Statement 2 is true.**

---