Solution of a salt in sulphanilic acid a naphithy lamine give red ppt ,due to

Options

A. `Br^(Theta)`
B. `I^(Theta)`
C. `NO_(2)^(Theta)`
D. `NO_(3)^(Theta)`

Answer

To solve the question regarding the formation of a red precipitate when a salt is treated with sulfanilic acid and naphthylamine, we will follow these steps:

### Step 1: Identify the Components
The question states that a solution of a salt is mixed with sulfanilic acid and naphthylamine. We need to identify the anion present in the salt that reacts with these reagents to form a red precipitate.

**Hint:** Look for the specific reactions that occur between the reagents and the possible anions.

### Step 2: Understand the Role of Naphthylamine
Naphthylamine is an aromatic amine that can react with certain anions to form colored precipitates. In this case, we are particularly interested in its reaction with iodide ions.

**Hint:** Recall the general reactions of aromatic amines with halides and how they can lead to colored products.

### Step 3: Reaction with Iodide Ion
When naphthylamine reacts with iodide ions, it forms a compound known as iodide naphthylamine. This compound can precipitate out of solution, resulting in a red precipitate.

**Hint:** Consider the structural aspects of the reaction and how the iodide ion interacts with naphthylamine.

### Step 4: Formation of the Red Precipitate
The red precipitate is specifically due to the formation of the iodide naphthylamine complex. The ortho position of the naphthylamine allows for the iodide ion to attach, leading to the characteristic red color.

**Hint:** Think about the significance of the ortho position in the formation of colored complexes.

### Step 5: Conclusion
Based on the above steps, we conclude that the anion responsible for the red precipitate when a salt is treated with sulfanilic acid and naphthylamine is the iodide ion.

**Final Answer:** The red precipitate is due to the presence of iodide ion in the salt.

### Summary of Steps:
1. Identify the components of the reaction.
2. Understand the role of naphthylamine.
3. Analyze the reaction with iodide ion.
4. Recognize the formation of the red precipitate.
5. Conclude that the iodide ion is responsible for the reaction.