Assertion : Decomposition of potassium chlorate is an example of redox reaction .
Reason : There is no change in the oxidation number of potassium in decomposition of potassium chlorate.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are true but reason is not the correct explanation of assertion.
C. If assertion is true but reason is false.
D. If both assertion and reason are false.

Explanation

To solve the question regarding the assertion and reason provided, we will analyze both statements step by step.

### Step 1: Analyze the Assertion
The assertion states that the decomposition of potassium chlorate (KClO3) is an example of a redox reaction.

1. **Write the Decomposition Reaction**:
The decomposition of potassium chlorate can be represented as:
\[ 2 \text{KClO}_3 \rightarrow 2 \text{KCl} + 3 \text{O}_2 \]

2. **Identify Oxidation States**:
- In KClO3:
- Potassium (K) = +1
- Chlorine (Cl) = +5 (calculated as follows: +1 (K) + 3*(-2 (O)) = 0 → +1 + x - 6 = 0 → x = +5)
- Oxygen (O) = -2
- In KCl:
- Potassium (K) = +1
- Chlorine (Cl) = -1 (calculated as follows: +1 (K) + x = 0 → +1 + x = 0 → x = -1)
- In O2 (free oxygen):
- Oxygen (O) = 0

3. **Determine Changes in Oxidation States**:
- Chlorine changes from +5 in KClO3 to -1 in KCl (reduction).
- Oxygen changes from -2 in KClO3 to 0 in O2 (oxidation).

4. **Conclusion on Assertion**:
Since both reduction and oxidation occur, the decomposition of potassium chlorate is indeed a redox reaction. Therefore, the assertion is **true**.

### Step 2: Analyze the Reason
The reason states that there is no change in the oxidation number of potassium in the decomposition of potassium chlorate.

1. **Examine Oxidation State of Potassium**:
- In both KClO3 and KCl, the oxidation state of potassium remains +1.

2. **Conclusion on Reason**:
The reason is also **true**; however, it does not explain why the reaction is a redox reaction. The redox nature of the reaction is due to the changes in oxidation states of chlorine and oxygen, not potassium.

### Final Conclusion
- **Assertion**: True (the decomposition of potassium chlorate is a redox reaction).
- **Reason**: True (there is no change in the oxidation number of potassium), but it does not explain the assertion.

### Answer
The correct option is that both the assertion and reason are true, but the reason is not the correct explanation for the assertion.