Fine the no of phases involved in thermal decomposition of `KCIO_(3)` in presence of `MnO_(2)(s)`.

Answer

To determine the number of phases involved in the thermal decomposition of potassium chlorate (KClO3) in the presence of manganese dioxide (MnO2), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reaction**:
The thermal decomposition of KClO3 in the presence of MnO2 can be represented as:
\[ 2 \text{KClO}_3 (s) \xrightarrow{\text{MnO}_2 (s)} 2 \text{KCl} (s) + 3 \text{O}_2 (g) \]
Here, KClO3 decomposes into potassium chloride (KCl) and oxygen gas (O2).

2. **Identify the States of Each Component**:
- KClO3 is a solid (s).
- MnO2 is a solid (s) and acts as a catalyst.
- KCl is a solid (s).
- O2 is a gas (g).

3. **Determine the Phases Present**:
- The solid phases present are KClO3, MnO2, and KCl.
- The gaseous phase present is O2.

4. **Consider the Decomposition**:
If we assume that KClO3 is completely decomposed, we will not consider KClO3 in the final phase count. The remaining components are:
- MnO2 (solid)
- KCl (solid)
- O2 (gas)

5. **Count the Phases**:
- Solid phase from MnO2: 1 phase
- Solid phase from KCl: 1 phase
- Gaseous phase from O2: 1 phase

Therefore, the total number of phases involved is:
\[ 1 \text{ (MnO}_2\text{)} + 1 \text{ (KCl)} + 1 \text{ (O}_2\text{)} = 3 \text{ phases} \]

### Final Answer:
The total number of phases involved in the thermal decomposition of KClO3 in the presence of MnO2 is **3**.

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