A green salt on heating decomposes to produce a colourless suffocating gas and leaves behind a reddish brown residue. Name the salt and write the decomposition reaction.

Explanation

To solve the problem, we need to identify the green salt, understand the decomposition reaction it undergoes upon heating, and write the balanced chemical equation for that reaction.

### Step-by-Step Solution:

1. **Identify the Green Salt:**
The question states that the salt is green in color. A common green salt that fits this description is ferrous sulfate, which is chemically represented as FeSO₄. This compound is often found in its heptahydrate form, FeSO₄·7H₂O, which is also green.

2. **Understand the Decomposition Reaction:**
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