A sodium salt `(A)` is heated with cone. Sulphuric acid. The evolved gas truns moist litmus paper red and producess white fumes in contact with a glass rod moistened with ammonia solution. It also gives white precipitate when passed through `AgNO_(3)` solution. When the salt is heated with `MnO_(2)` and cone. `H_(2)SO_(4)`, a gas with an irritating smell is evolved which turns starch-iodide paper blue. Identify the salt and the gaseous product evolved from it. Explain your answer with relevant chemical equations.

Explanation

To solve the problem, we need to identify the sodium salt (A) and the gaseous products evolved when it is treated with concentrated sulfuric acid and manganese dioxide (MnO2). Let's break down the steps:

### Step 1: Identify the Sodium Salt
The sodium salt (A) mentioned in the question is likely sodium chloride (NaCl). This is a common sodium salt that reacts with concentrated sulfuric acid.

### Step 2: Reaction with Concentrated Sulfuric Acid
When sodium chloride (NaCl) is heated with concentrated sulfuric acid (H2SO4), the following reaction occurs:

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