`KCIO_(3)` on heating decomposes into KCl and `O_(2)`. If some `MnO_(2)` is added the reaction goes much faster because : 

Options

A. `MnO_(2)` decomposes to give oxygen
B. `MnO_(2)` provides heat by reacting
C. better contact is provided by `MnO_(2)`
D. `MnO_(2)` acts as a catalyst

Answer

To solve the question regarding the decomposition of potassium chlorate (KClO₃) when heated and the role of manganese dioxide (MnO₂) in this reaction, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Reaction**:
The decomposition of potassium chlorate (KClO₃) upon heating can be represented by the following chemical equation:
\[ 2 \, KClO_3 \, (s) \rightarrow 2 \, KCl \, (s) + 3 \, O_2 \, (g) \]
This indicates that when KClO₃ is heated, it breaks down into potassium chloride (KCl) and oxygen gas (O₂).

2. **Identify the Role of MnO₂**:
When manganese dioxide (MnO₂) is added to the reaction, it acts as a catalyst. A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the process.

3. **Explain Why the Reaction Goes Faster**:
The presence of MnO₂ lowers the activation energy required for the decomposition of KClO₃. This means that the reaction can occur more readily and at a faster rate.

4. **Conclusion**:
Therefore, the correct reason for the increased rate of the reaction when MnO₂ is added is that MnO₂ acts as a catalyst.

### Final Answer:
The reaction goes much faster because MnO₂ acts as a catalyst.

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