Mention an example in which `H_2O` acts as reducing agent.

Answer

To determine an example in which water (H₂O) acts as a reducing agent, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Reducing Agents**: A reducing agent is a substance that donates electrons to another substance, causing the other substance to be reduced. In the process, the reducing agent itself gets oxidized.

2. **Identifying Strong Electron Acceptors**: Water can act as a reducing agent when it reacts with a strong electron acceptor. A strong electron acceptor is typically a substance that has a high tendency to gain electrons.

3. **Example Reaction**: One well-known example is the reaction of water with fluorine (F₂). Fluorine is a very strong oxidizing agent and can accept electrons readily.

4. **Chemical Reaction**: The reaction can be represented as follows:
\[ 2 H_2O + 2 F_2 \rightarrow 4 HF + O_2 \]
In this reaction, water (H₂O) is oxidized to oxygen (O₂), while fluorine (F₂) is reduced to hydrofluoric acid (HF).

5. **Conclusion**: In this reaction, water acts as a reducing agent because it donates electrons to fluorine, which is reduced in the process.

### Summary:
Water (H₂O) acts as a reducing agent when it reacts with fluorine (F₂) to produce hydrofluoric acid (HF) and oxygen (O₂).

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