Assertion :- Nitrous acid `(HNO_(2))` may act as an oxidising agent as well as a reducing agent.
Reason :- The oxidation number of Nitrogen remains same in all the compounds.

Options

A. If both Assertion & Reason are True & the Reason is a correct explanation of the Assertion.
B. If both Assertion & Reason are True but Reason is not a correct explanation of the Assertion.
C. If Assertion is True but the Reason is False.
D. If both Assertion & Reason are False.

Answer

To solve the question, we will analyze the assertion and reason step by step.

### Step 1: Analyze the Assertion
The assertion states that nitrous acid (HNO₂) may act as both an oxidizing agent and a reducing agent.

1. **Determine the oxidation state of nitrogen in HNO₂**:
- The oxidation state of hydrogen (H) is +1.
- The oxidation state of oxygen (O) is -2.
- Let the oxidation state of nitrogen (N) be \( x \).
- The equation for the compound is:
\[ +1 + x + 2(-2) = 0 \]
- Simplifying this gives:
\[ +1 + x - 4 = 0 \implies x - 3 = 0 \implies x = +3 \]
- Therefore, the oxidation state of nitrogen in HNO₂ is +3.

2. **Determine the possible changes in oxidation state**:
- Nitrogen can have oxidation states ranging from -3 to +5 in various compounds.
- If nitrogen in HNO₂ is reduced from +3 to a lower oxidation state (e.g., -3), it acts as an oxidizing agent.
- Conversely, if nitrogen is oxidized from +3 to a higher oxidation state (e.g., +5), it acts as a reducing agent.

### Conclusion for Assertion:
Since nitrogen in HNO₂ can change its oxidation state, the assertion that nitrous acid may act as both an oxidizing agent and a reducing agent is **true**.

### Step 2: Analyze the Reason
The reason states that the oxidation number of nitrogen remains the same in all compounds.

1. **Evaluate the statement**:
- The oxidation state of nitrogen is not constant; it varies in different compounds.
- For example:
- In NH₃, the oxidation state of nitrogen is -3.
- In NO, the oxidation state of nitrogen is +2.
- In NO₃⁻, the oxidation state of nitrogen is +5.
- Therefore, nitrogen has a variable oxidation state.

### Conclusion for Reason:
The reason that the oxidation number of nitrogen remains the same in all compounds is **false**.

### Final Conclusion:
- The assertion is **true**.
- The reason is **false**.
- Thus, the correct answer is option C: Assertion is true, but the reason is false.

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