Assertion : Decomposition of hydrogen peroxide is an example of disproportionation reaction.
Reason : In a disproportionation reaction, an element in one oxidation state is simultaneously oxidised and reduced .

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.

Answer

To solve the question regarding the assertion and reason about the decomposition of hydrogen peroxide, we will analyze both statements step by step.

### Step 1: Understanding the Assertion
The assertion states that the decomposition of hydrogen peroxide (H₂O₂) is an example of a disproportionation reaction.

**Reaction:**
The decomposition of hydrogen peroxide can be represented as:
\[ 2 \text{H}_2\text{O}_2 \rightarrow 2 \text{H}_2\text{O} + \text{O}_2 \]

### Step 2: Analyzing the Oxidation States
Next, we need to determine the oxidation states of the elements involved in the reaction.

1. **In H₂O₂:**
- Hydrogen (H) has an oxidation state of +1.
- Let the oxidation state of Oxygen (O) be \( x \).
- The equation for the oxidation state in H₂O₂ is:
\[ 2(+1) + 2x = 0 \]
\[ 2 + 2x = 0 \]
\[ 2x = -2 \]
\[ x = -1 \]
- Thus, in H₂O₂, the oxidation state of oxygen is -1.

2. **In H₂O:**
- The oxidation state of H is still +1.
- Let the oxidation state of O be \( y \).
- The equation for the oxidation state in H₂O is:
\[ 2(+1) + y = 0 \]
\[ 2 + y = 0 \]
\[ y = -2 \]
- Thus, in H₂O, the oxidation state of oxygen is -2.

3. **In O₂:**
- The oxidation state of oxygen in its elemental form (O₂) is 0.

### Step 3: Identifying Oxidation and Reduction
Now, we can identify the changes in oxidation states:

- **From H₂O₂ to H₂O:**
- Oxygen changes from -1 (in H₂O₂) to -2 (in H₂O), which is a reduction (gain of electrons).

- **From H₂O₂ to O₂:**
- Oxygen changes from -1 (in H₂O₂) to 0 (in O₂), which is an oxidation (loss of electrons).

### Step 4: Conclusion on the Assertion
Since the same element (oxygen) is undergoing both oxidation and reduction in the same reaction, the assertion is true. This is characteristic of a disproportionation reaction.

### Step 5: Understanding the Reason
The reason states that in a disproportionation reaction, an element in one oxidation state is simultaneously oxidized and reduced. This is indeed true as it describes the nature of disproportionation reactions accurately.

### Final Conclusion
Both the assertion and reason are true, and the reason correctly explains the assertion. Therefore, the correct answer is that both the assertion and reason are true, and the reason is the correct explanation of the assertion.

### Answer:
Both assertion and reason are true, and the reason is the correct explanation of the assertion.

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