Among oxyacids of nitrogen `HNO_(2)` is unstable, it can acts as

Options

A. Oxidising agent
B. Reducing agent
C. Oxidising agent and Reducing agent
D. None

Answer

To solve the question regarding the behavior of nitrous acid (HNO₂) as an oxidizing agent, reducing agent, or both, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Oxidation State of Nitrogen in HNO₂**:
- In HNO₂, the oxidation state of nitrogen can be calculated as follows:
- Oxygen (O) has an oxidation state of -2.
- There are two oxygen atoms, contributing a total of -4.
- Hydrogen (H) has an oxidation state of +1.
- Let the oxidation state of nitrogen (N) be x.
- The overall charge of the molecule is neutral (0).
- Therefore, the equation can be set up as:
\[ x + 1 + (-4) = 0 \implies x - 3 = 0 \implies x = +3 \]
- Thus, the oxidation state of nitrogen in HNO₂ is +3.

**Hint**: Remember that the sum of oxidation states in a neutral compound is zero.

2. **Determine the Range of Oxidation States for Nitrogen**:
- The highest oxidation state of nitrogen is +5 (in nitric acid, HNO₃).
- The lowest oxidation state of nitrogen is -3 (in ammonia, NH₃).
- Since +3 is between -3 and +5, HNO₂ can potentially act as both an oxidizing agent and a reducing agent.

**Hint**: Identify the highest and lowest oxidation states of an element to determine its potential as an oxidizing or reducing agent.

3. **Analyze the Behavior of HNO₂**:
- **As an Oxidizing Agent**:
- HNO₂ can oxidize other substances. For example, it can oxidize hydrogen sulfide (H₂S) to sulfur (S):
\[ 2 \text{HNO}_2 + \text{H}_2\text{S} \rightarrow \text{S} + 2 \text{H}_2\text{O} + 2 \text{NO} \]
- In this reaction, H₂S is oxidized (the oxidation state of sulfur changes from -2 to 0).

**Hint**: Look for reactions where the substance gains oxygen or loses electrons to identify oxidizing behavior.

4. **As a Reducing Agent**:
- HNO₂ can also act as a reducing agent. For example, it can reduce bromine (Br₂) to hydrobromic acid (HBr):
\[ \text{HNO}_2 + \text{Br}_2 + \text{H}_2\text{O} \rightarrow 2 \text{HBr} + \text{HNO}_3 \]
- In this reaction, bromine is reduced (the oxidation state of bromine changes from 0 to -1).

**Hint**: Identify reactions where the substance loses oxygen or gains electrons to determine reducing behavior.

5. **Conclusion**:
- Since HNO₂ can act as both an oxidizing agent and a reducing agent, the correct answer to the question is that HNO₂ acts as both.

### Final Answer:
HNO₂ can act as both an oxidizing agent and a reducing agent.