Two colourless gas A and B are enclosed in two separate jars. When passed through acidified `K_(2)Cr_(2)O_(7)` solution, turn the solution green. But gas A turns lead acetate paper black whereas if both the gases are passed into water, the solution develops a yellowish white turbidity. Identify the gases A and B and write balanced equations for the chemical reactions taking place.

Explanation

To identify the gases A and B, we will analyze the information provided step by step.

### Step 1: Analyze the properties of gas A
- **Observation**: Gas A turns lead acetate paper black.
- **Conclusion**: This indicates that gas A is hydrogen sulfide (H₂S), as H₂S reacts with lead acetate to form lead sulfide (PbS), which is black.

### Step 2: Analyze the properties of gas B
- **Observation**: Both gases A and B turn acidified potassium dichromate (K₂Cr₂O₇) solution green.
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