A solid laboratory reagent (A) give following reactions.
(i) It impart green colour of flame :
(ii) Its solution does not give ppt. on passong `H_(2)S`.
(iii) When it is heated with `K_(2)Cr_(2)O_(7)` and conc. `H_(2)SO_(4)`, a red gas (B) is evolved. The gas when passed in aq. NaOH solution turns it yellow (C). Identify (A), (B), (C) giving chemical reactions.

Explanation

To solve the given problem step by step, we will analyze each part of the question and identify the compounds involved.

### Step 1: Identify Reagent A
The first clue is that the solid laboratory reagent (A) imparts a green color to the flame.

**Solution:**
The green color in the flame test is characteristic of barium ions (Ba²⁺). Therefore, we can conclude that:
- **A = Barium chloride (BaCl₂)**
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