Consider three P, Q, R, salts among them P and Q salts have different cations annd also have different coloured polyatomic anion due to charge transfer phenomenon while P and R salts have same cation but have different anions. Salts R decomposes into an acidic gas an a basic gas.
Q. Salt P decomposes on heating into a coloured solid, neutral gas a neutral vapour, then which of the following can not be the product of salt P after decomposition?

Options

A. `N_(2)`
B. `Cr_(2)O_(3)`
C. `I_(2)`
D. `H_(2)O`

Explanation

To solve the problem, we need to analyze the decomposition of salt P based on the information provided.

### Step-by-Step Solution:

1. **Identify Salt P**:
- From the context, we can infer that salt P is likely ammonium dichromate, represented as \( \text{NH}_4\text{Cr}_2\text{O}_7 \). This salt is known for its decomposition upon heating.

2. **Decomposition Reaction**:
- When ammonium dichromate is heated, it decomposes into:
\[ \text{NH}_4\text{Cr}_2\text{O}_7 \rightarrow \text{N}_2 + \text{Cr}_2\text{O}_3 + \text{H}_2\text{O} \]
- Here, \( \text{N}_2 \) is a neutral gas, \( \text{Cr}_2\text{O}_3 \) is a colored solid, and \( \text{H}_2\text{O} \) is a neutral vapor.

3. **Identify Possible Products**:
- From the decomposition reaction, we have:
- Colored solid: \( \text{Cr}_2\text{O}_3 \)
- Neutral gas: \( \text{N}_2 \)
- Neutral vapor: \( \text{H}_2\text{O} \)

4. **Determine the Incorrect Product**:
- The question asks which of the following cannot be a product of salt P after decomposition.
- Given the products from the decomposition reaction, we need to identify an option that does not appear in the decomposition products.
- For instance, if one of the options is \( \text{I}_2 \) (iodine), it is not produced in the decomposition of ammonium dichromate.

5. **Conclusion**:
- Therefore, the product that cannot be formed from the decomposition of salt P is \( \text{I}_2 \).

### Final Answer:
The product that cannot be the result of the decomposition of salt P is \( \text{I}_2 \).

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