On addition of conc. `H_(2)SO_(4)` to a chloride salt, colourless fumes are evolved but in case of iodide salt, violet fumes come out. This is because

Options

A. 1. `H_(2)SO_(4)" reduces "HI" to "I_(2)`
B. 2. HI is of violet colour
C. 3. HI gets oxidised to `I_(2)`
D. 4. HI changes to `HIO_(3)`.

Explanation

To understand why the addition of concentrated sulfuric acid to chloride salts produces colorless fumes while the same addition to iodide salts produces violet fumes, we can break down the reactions step by step.

### Step-by-Step Solution:

1. **Identify the Chloride Salt Reaction**:
- Let's consider sodium chloride (NaCl) as an example of a chloride salt.
- When concentrated sulfuric acid (H₂SO₄) is added to sodium chloride, the reaction can be represented as:
\[ \text{NaCl} + \text{H}_2\text{SO}_4 \rightarrow \text{HCl} + \text{NaHSO}_4 \]
- Here, hydrochloric acid (HCl) is produced, which is a colorless gas.

2. **Identify the Iodide Salt Reaction**:
- Now, let's consider sodium iodide (NaI) as an example of an iodide salt.
- When concentrated sulfuric acid is added to sodium iodide, the reaction can be represented as:
\[ \text{NaI} + \text{H}_2\text{SO}_4 \rightarrow \text{HI} + \text{NaHSO}_4 \]
- Hydrogen iodide (HI) is produced initially, which is also a colorless gas.

3. **Oxidation of Hydrogen Iodide**:
- The hydrogen iodide (HI) can further react with concentrated sulfuric acid:
\[ \text{HI} + \text{H}_2\text{SO}_4 \rightarrow \text{I}_2 + \text{SO}_2 + \text{H}_2\text{O} \]
- In this reaction, hydrogen iodide is oxidized to iodine (I₂), which is a violet gas. The sulfuric acid acts as an oxidizing agent.

4. **Conclusion**:
- The key difference is that in the case of chloride salts, the product (HCl) is colorless and does not undergo further oxidation. In contrast, with iodide salts, hydrogen iodide is oxidized to iodine, which is responsible for the violet fumes observed.

### Final Answer:
The colorless fumes from chloride salts are due to the production of hydrochloric acid, while the violet fumes from iodide salts are due to the oxidation of hydrogen iodide to iodine by sulfuric acid.