An inorganic salt when heated with concentrated `H_(2)SO_(4)` evolves a colourless pungent smelling gas but with concentrated `H_(2)SO_(4)` and `MnO_(2)` evolves a coloured pungent smelling gas which bleaches moist litmus paper.The coloured gas is:

Options

A. `NO_(2)`
B. `Cl_(2)`
C. `Br_(2)`
D. `I_(2)`

Explanation

To solve the problem, we will analyze the reactions described in the question step by step.

### Step 1: Identify the Inorganic Salt
The question states that an inorganic salt, when heated with concentrated sulfuric acid (H₂SO₄), evolves a colorless pungent-smelling gas. A common inorganic salt that fits this description is sodium chloride (NaCl). When sodium chloride is heated with concentrated H₂SO₄, it produces hydrogen chloride (HCl) gas, which is colorless and has a pungent smell.

### Step 2: Reaction with Concentrated H₂SO₄
The reaction can be represented as:
\[ \text{NaCl (s) + H₂SO₄ (l) → NaHSO₄ (s) + HCl (g)} \]
Here, HCl is the colorless gas that is evolved.

### Step 3: Reaction with MnO₂ and Concentrated H₂SO₄
Next, the question mentions that when the same inorganic salt (NaCl) is treated with concentrated H₂SO₄ and manganese dioxide (MnO₂), a colored pungent-smelling gas is evolved that bleaches moist litmus paper.

In this case, the MnO₂ acts as an oxidizing agent and facilitates the oxidation of chloride ions (Cl⁻) to chlorine gas (Cl₂). The reaction can be represented as:
\[ 2 \text{NaCl (s) + 2 H₂SO₄ (l) + MnO₂ (s) → Cl₂ (g) + MnSO₄ (s) + 2 H₂O (l)} \]

### Step 4: Identify the Colored Gas
Chlorine gas (Cl₂) is yellowish-green in color and has a pungent smell. It is known for its bleaching properties, which is why it can bleach moist litmus paper.

### Conclusion
Thus, the colored gas that evolves when the inorganic salt is treated with concentrated H₂SO₄ and MnO₂ is chlorine gas (Cl₂).

### Final Answer
The colored gas is chlorine (Cl₂).

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