`FeSO_(4).7H_(2)O` (Green vitriol) salt on thermal decomposition does not produce:

Options

A. `SO_(2)`
B. `O_(2)`
C. `SO_(3)`
D. `H_(2)O` vapour

Explanation

To solve the question regarding the thermal decomposition of `FeSO4.7H2O` (Green vitriol), we will analyze the decomposition process step by step.

### Step 1: Understand the Composition of Green Vitriol
Green vitriol is composed of iron(II) sulfate and seven molecules of water. Its chemical formula is `FeSO4.7H2O`.

### Step 2: Identify the Thermal Decomposition Process
When `FeSO4.7H2O` is heated, it undergoes thermal decomposition. The first step involves the loss of water molecules.

### Step 3: Write the Initial Decomposition Reaction
On heating, `FeSO4.7H2O` decomposes as follows:
\[ FeSO4.7H2O \rightarrow FeSO4 + 7H2O \]
This shows that water vapor is released during the decomposition.

### Step 4: Further Decomposition of Iron(II) Sulfate
When `FeSO4` is further heated, it decomposes into iron(III) oxide, sulfur dioxide, and sulfur trioxide:
\[ 2FeSO4 \rightarrow Fe2O3 + SO2 + SO3 \]

### Step 5: Identify the Products Formed
From the above reactions, we can identify the products formed during the thermal decomposition:
- Water vapor (`H2O`)
- Sulfur dioxide (`SO2`)
- Sulfur trioxide (`SO3`)

### Step 6: Analyze the Options Given
The question asks which compound is **not** produced during the thermal decomposition. The options are:
1. SO2
2. O2
3. SO3
4. H2O

From our analysis:
- SO2 is produced.
- SO3 is produced.
- H2O (water vapor) is produced.
- O2 (oxygen) is **not** produced.

### Conclusion
The correct answer is that `O2` is not produced during the thermal decomposition of `FeSO4.7H2O`.

### Final Answer
**O2** is not produced during the thermal decomposition of `FeSO4.7H2O`.

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