In which of the following reaction dihydron acts as an oxidising agent?

Options

A. `Ca+H_(2)toCaH_(2)`
B. `2H_(2)+O_(2)to2H_(2)O`
C. `H_(2)+F_(2)to2HF`
D. `CuO+H_(2)toCu+H_(2)O`

Explanation

To determine in which of the given reactions dihydrogen (H₂) acts as an oxidizing agent, we need to analyze the oxidation states of the elements involved in each reaction. An oxidizing agent is a substance that gains electrons (is reduced) and, in the process, causes another substance to be oxidized (lose electrons).

### Step-by-Step Solution:

1. **Understand the Concept of Oxidizing and Reducing Agents:**
- An oxidizing agent is an electron acceptor, meaning it gains electrons and gets reduced.
- A reducing agent is an electron donor, meaning it loses electrons and gets oxidized.

2. **Analyze Each Reaction:**
- **Reaction 1:** Calcium + Dihydrogen → Calcium Hydride (CaH₂)
- Oxidation states: Ca (0) → Ca (+2), H (0) → H (-1)
- Here, calcium is oxidized (loses electrons), and dihydrogen is reduced (gains electrons). Thus, dihydrogen acts as an oxidizing agent.

- **Reaction 2:** Dihydrogen + Oxygen → Water (H₂O)
- Oxidation states: H (0) → H (+1), O (0) → O (-2)
- Here, dihydrogen is oxidized (loses electrons), and oxygen is reduced (gains electrons). Thus, dihydrogen acts as a reducing agent.

- **Reaction 3:** Dihydrogen + Fluorine → Hydrogen Fluoride (HF)
- Oxidation states: H (0) → H (+1), F (0) → F (-1)
- Here, dihydrogen is oxidized (loses electrons), and fluorine is reduced (gains electrons). Thus, dihydrogen acts as a reducing agent.

- **Reaction 4:** Copper(II) Oxide + Dihydrogen → Copper + Water
- Oxidation states: Cu (+2) → Cu (0), H (0) → H (+1)
- Here, copper is reduced (gains electrons), and dihydrogen is oxidized (loses electrons). Thus, dihydrogen acts as a reducing agent.

3. **Conclusion:**
- From the analysis, only in **Reaction 1** does dihydrogen act as an oxidizing agent. In all other reactions, dihydrogen acts as a reducing agent.

### Final Answer:
Dihydrogen acts as an oxidizing agent in **Reaction 1** (Calcium + Dihydrogen → Calcium Hydride).

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