Which of the following can acts as both oxidant and redutant

Options

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

Answer

To determine which of the given compounds can act as both an oxidant and a reductant, we need to analyze their oxidation states. The ability of a substance to act as both an oxidant (electron acceptor) and a reductant (electron donor) typically requires it to have an intermediate oxidation state.

### Step-by-Step Solution:

1. **Identify the Compounds**: The compounds given are H2N2O2 (Hyponitrous acid), HNO2 (Nitrous acid), HNO3 (Nitric acid), and HNO4 (Per nitric acid).

2. **Determine the Oxidation States**:
- **For H2N2O2**:
- Assign oxidation states: H = +1, O = -2.
- The equation becomes: 2(+1) + 2(N) + 2(-2) = 0.
- Simplifying gives: 2 + 2N - 4 = 0 → 2N - 2 = 0 → N = +1.
- This is not a middle oxidation state.

- **For HNO2**:
- Assign oxidation states: H = +1, O = -2.
- The equation becomes: +1 + N + 2(-2) = 0.
- Simplifying gives: 1 + N - 4 = 0 → N - 3 = 0 → N = +3.
- This is a middle oxidation state.

- **For HNO3**:
- Assign oxidation states: H = +1, O = -2.
- The equation becomes: +1 + N + 3(-2) = 0.
- Simplifying gives: 1 + N - 6 = 0 → N - 5 = 0 → N = +5.
- This is not a middle oxidation state.

- **For HNO4**:
- Assign oxidation states: H = +1, O = -2.
- The equation becomes: +1 + N + 4(-2) = 0.
- Simplifying gives: 1 + N - 8 = 0 → N - 7 = 0 → N = +7.
- This is not a middle oxidation state.

3. **Conclusion**:
- The only compound that has a middle oxidation state is HNO2 (Nitrous acid), which has an oxidation state of +3. This allows it to act as both an oxidant and a reductant, as it can either gain electrons (be reduced) or lose electrons (be oxidized).

### Final Answer:
The compound that can act as both an oxidant and a reductant is **HNO2 (Nitrous acid)**.

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