A salt which on hearing with conc. `H_2 SO_4` gives violet vapours is

Options

A. lodide salt
B. Nitrate salt
C. Sulphate salt
D. Bromide salt

Answer

To solve the question about which salt produces violet vapors upon heating with concentrated sulfuric acid (H₂SO₄), we can follow these steps:

### Step 1: Identify the Reaction
When a salt is heated with concentrated sulfuric acid, a chemical reaction occurs. We need to identify which salt produces violet vapors. The violet vapors are typically associated with iodine (I₂).

### Step 2: Consider Common Salts
The common salts that can be heated with concentrated H₂SO₄ include:
- Sodium iodide (NaI)
- Potassium iodide (KI)
- Sodium bromide (NaBr)
- Potassium bromide (KBr)

Among these, iodides (like KI) are known to produce iodine vapors when reacted with concentrated sulfuric acid.

### Step 3: Write the Reaction for KI
Let's consider potassium iodide (KI) as an example:
\[ 2 KI + H_2SO_4 \rightarrow 2 KHSO_4 + I_2 + H_2 \]
In this reaction, when potassium iodide is heated with concentrated sulfuric acid, it produces iodine (I₂), which is known to have a violet color in vapor form.

### Step 4: Conclusion
Since the violet vapors are due to the formation of iodine gas, we can conclude that the salt which produces violet vapors when heated with concentrated H₂SO₄ is potassium iodide (KI).

### Final Answer
The salt which on heating with concentrated H₂SO₄ gives violet vapors is **Potassium Iodide (KI)**.

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