Chlorine gas is passed into a solution containing KF, KI and KBr and `CHCl _3` ​ is added. The initial colour in `CHCI_3` ​ layer is:

Explanation

To solve the problem, we need to analyze the reaction that occurs when chlorine gas is passed into a solution containing KF, KI, and KBr, followed by the addition of CHCl3 (chloroform).

### Step-by-Step Solution:

1. **Identify the Components**: The solution contains potassium fluoride (KF), potassium iodide (KI), and potassium bromide (KBr). When chlorine gas (Cl2) is introduced, it can react with the iodide (I-) and bromide (Br-) ions present in the solution.

2. **Understand the Reactivity**: Chlorine is a strong oxidizing agent. It can oxidize iodide ions (I-) to iodine (I2). The reduction potential of iodide is lower than that of bromide, meaning that iodide will be oxidized preferentially over bromide.

3. **Write the Reaction**: The reaction that occurs when chlorine gas is passed into the solution can be represented as:
\[ Cl_2 + 2KI \rightarrow 2KCl + I_2 \]
Here, chlorine oxidizes iodide ions to iodine.

4. **Formation of Iodine**: The iodine (I2) formed in the reaction is not soluble in water but is soluble in organic solvents like chloroform (CHCl3). When the chloroform is added to the solution, the iodine will dissolve in the chloroform layer.

5. **Color of the Chloroform Layer**: Iodine imparts a characteristic violet color to the chloroform layer. Therefore, after the reaction and the addition of chloroform, the initial color observed in the chloroform layer will be violet due to the presence of dissolved iodine.

### Final Answer:
The initial color in the CHCl3 layer is violet due to the formation of iodine.

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