In layer test of `I^(-)` and `Br^(-)`. If reddish -brown layer comes first then -

Options

A. `Br^(-)` present
B. `I^(-)` absent
C. Both (1) and (2)
D. None of these

Answer

To solve the question regarding the layer test for iodide (I^(-)) and bromide (Br^(-)) ions, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Layer Test**: The layer test is a qualitative analysis method used to identify the presence of halide ions, specifically iodide and bromide ions, in a solution.

2. **Prepare the Solution**: Start with the solution that potentially contains iodide or bromide ions.

3. **Acidify the Solution**: Add dilute nitric acid (HNO₃) to the solution. This step is crucial as it helps to remove any interfering ions and ensures that the halides are in their ionic form.

4. **Add Chlorine Water**: Introduce chlorine water (a solution of Cl₂ in water) to the acidified solution. Chlorine acts as an oxidizing agent and will react with the halide ions.

5. **Add Organic Solvent**: After adding chlorine water, add an organic solvent such as chloroform (CHCl₃) or carbon disulfide (CS₂) to the mixture. This solvent will help in the extraction of the halogen.

6. **Shake the Mixture**: Shake the mixture thoroughly. This allows for the formation of layers, where the organic solvent will separate from the aqueous phase.

7. **Observe the Layers**: After shaking, observe the color of the organic layer:
- If a **reddish-brown layer** appears, it indicates the presence of **bromide ions (Br^(-))**.
- If a **violet layer** appears, it indicates the presence of **iodide ions (I^(-))**.

8. **Conclusion**: Since the question states that a reddish-brown layer appears first, we conclude that **bromide ions (Br^(-))** are present in the solution.

### Final Answer:
If a reddish-brown layer comes first in the layer test, it indicates the presence of bromide ions (Br^(-)).

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