Which of the following act both as an oxidising as well as reducing agent ?

Options

A. `HNO_(3)`
B. `H_(2)SO_(4)`
C. `H_(2)O_(2)`
D. `HNO_(2)`

Answer

To determine which of the given compounds can act as both an oxidizing agent and a reducing agent, we will analyze each option based on the oxidation states of the elements involved.

### Step-by-Step Solution:

1. **Understanding Oxidizing and Reducing Agents**:
- An oxidizing agent is a substance that gains electrons and is reduced in a chemical reaction.
- A reducing agent is a substance that loses electrons and is oxidized in a chemical reaction.
- A compound can act as both if it has elements in both their highest and lowest oxidation states.

2. **Analyzing Each Compound**:
- **Option 1: HNO3 (Nitric Acid)**:
- The oxidation state of nitrogen (N) in HNO3 can be calculated:
- H: +1, O: -2 (3 O atoms contribute -6)
- Let the oxidation state of N be \( x \).
- The equation is: \( +1 + x - 6 = 0 \)
- Solving gives \( x = +5 \).
- Since nitrogen is in its highest oxidation state (+5), HNO3 can only act as an oxidizing agent.

- **Option 2: H2SO4 (Sulfuric Acid)**:
- The oxidation state of sulfur (S) in H2SO4 can be calculated:
- H: +1 (2 H atoms contribute +2), O: -2 (4 O atoms contribute -8)
- Let the oxidation state of S be \( y \).
- The equation is: \( +2 + y - 8 = 0 \)
- Solving gives \( y = +6 \).
- Since sulfur is also in its highest oxidation state (+6), H2SO4 can only act as an oxidizing agent.

- **Option 3: H2O2 (Hydrogen Peroxide)**:
- The oxidation state of oxygen (O) in H2O2 can be calculated:
- H: +1 (2 H atoms contribute +2), O: let it be \( z \) (2 O atoms contribute \( 2z \)).
- The equation is: \( +2 + 2z = 0 \)
- Solving gives \( z = -1 \).
- In H2O2, oxygen is in the -1 oxidation state. It can lose electrons to go to 0 (acting as a reducing agent) or gain electrons to go to -2 (acting as an oxidizing agent). Thus, H2O2 can act as both an oxidizing and a reducing agent.

- **Option 4: HNO2 (Nitrous Acid)**:
- The oxidation state of nitrogen (N) in HNO2 can be calculated:
- H: +1, O: -2 (2 O atoms contribute -4)
- Let the oxidation state of N be \( w \).
- The equation is: \( +1 + w - 4 = 0 \)
- Solving gives \( w = +3 \).
- Since nitrogen is in a +3 oxidation state, HNO2 can act as a reducing agent but not as an oxidizing agent.

3. **Conclusion**:
- From the analysis, only H2O2 can act as both an oxidizing agent and a reducing agent.

### Final Answer:
**H2O2 (Hydrogen Peroxide)** acts as both an oxidizing agent and a reducing agent.