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 and determine their validity.

### Step-by-Step Solution:

**Step 1: Evaluate Statement 1**
- **Statement 1**: `KMnO4` is colored due to d-d transition.
- **Analysis**: In `KMnO4`, manganese (Mn) is in the +7 oxidation state. The electronic configuration of Mn in this state is 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁰, meaning there are no d electrons present (3d orbitals are empty). Since d-d transitions require the presence of d electrons to transition between different d orbitals, and there are no d electrons in `KMnO4`, this statement is **false**. The color of `KMnO4` is actually due to charge transfer transitions rather than d-d transitions.

**Step 2: Evaluate Statement 2**
- **Statement 2**: Colour due to d-d transition will be less intense.
- **Analysis**: d-d transitions typically have a smaller energy gap between the d orbitals, which results in less intense colors. This is because the intensity of the color is related to the probability of the transition occurring, which is lower when the energy difference between the d orbitals is small. Therefore, this statement is **true**.

**Step 3: Evaluate Statement 3**
- **Statement 3**: `Fe[Fe(CN)6]` will retain a brown-colored complex after a long time of its formation.
- **Analysis**: The complex `Fe[Fe(CN)6]` actually forms a blue-colored complex known as Prussian blue, not a brown-colored one. Therefore, this statement is also **false**.

### Conclusion:
- Statement 1: False
- Statement 2: True
- Statement 3: False

Thus, the overall evaluation of the statements is:
- Statement 1: False
- Statement 2: True
- Statement 3: False

The answer is **B** (False, True, False).