`H_(2)O_(2)` can act as

Options

A. oxidising agent
B. Reducing agent
C. Bleaching agent
D. Acid

Answer

To determine the roles of hydrogen peroxide (H₂O₂), we will analyze its behavior as an oxidizing agent, reducing agent, bleaching agent, and acid.

### Step-by-Step Solution:

1. **Identify the Oxidation States**:
- In H₂O₂, the oxidation state of oxygen is -1. This is important for understanding its ability to act as both an oxidizing and reducing agent.

2. **H₂O₂ as an Oxidizing Agent**:
- An oxidizing agent is a substance that oxidizes other substances while being reduced itself.
- H₂O₂ can be reduced to water (H₂O), where the oxidation state of oxygen changes from -1 in H₂O₂ to -2 in H₂O.
- This means H₂O₂ can accept electrons and protons to form water, thus acting as an oxidizing agent in both acidic and basic mediums.
- **Example Reaction**:
\[ \text{FeSO}_4 + \text{H}_2\text{SO}_4 + \text{H}_2\text{O}_2 \rightarrow \text{Fe}_2(\text{SO}_4)_3 + \text{H}_2\text{O} \]
- In this reaction, Fe²⁺ (oxidation state +2) is oxidized to Fe³⁺ (oxidation state +3), while H₂O₂ is reduced to water.

3. **H₂O₂ as a Reducing Agent**:
- H₂O₂ can also act as a reducing agent in the presence of a strong oxidizing agent.
- In this case, H₂O₂ is oxidized to molecular oxygen (O₂), changing the oxidation state of oxygen from -1 in H₂O₂ to 0 in O₂.
- **Example Reaction**:
\[ \text{K}_2\text{Cr}_2\text{O}_7 + \text{H}_2\text{SO}_4 + \text{H}_2\text{O}_2 \rightarrow \text{K}_2\text{SO}_4 + \text{Cr}_2(\text{SO}_4)_3 + \text{H}_2\text{O} + \text{O}_2 \]
- Here, Cr⁶⁺ (in K₂Cr₂O₇) is reduced to Cr³⁺ (in Cr₂(SO₄)₃), while H₂O₂ is oxidized to O₂.

4. **H₂O₂ as a Bleaching Agent**:
- H₂O₂ can act as a bleaching agent due to its ability to release nascent oxygen upon decomposition.
- The nascent oxygen can react with colored substances, oxidizing them and effectively bleaching them.
- **General Reaction**:
\[ \text{Coloring Matter} + \text{Nascent Oxygen} \rightarrow \text{Bleached Product} \]

5. **H₂O₂ as an Acid**:
- H₂O₂ is not typically classified as an acid. It does not donate protons (H⁺) in the way that acids do. Therefore, it does not act as an acid in the traditional sense.

### Conclusion:
From the analysis, we conclude that H₂O₂ can act as:
- An **oxidizing agent** (A)
- A **reducing agent** (B)
- A **bleaching agent** (C)

However, it does not act as an **acid** (D). Therefore, the correct options are A, B, and C.