Which of the following involves the reduction of copper?

Options

A. `Cu(s)+1//2O_(2)(g) rarr CuO(s)`
B. `Cu^( 2+)(aq)+2l^(-)(aq) rarr 2C"ul"(aq)`
C. `CuCl_(2)(s)+2F^(-)(aq) rarr CuF_(2)+Cl_(2)(g)`
D. `CuO+H_(2)O rarr Cu(OH)_(2)`

Answer

To determine which of the given options involves the reduction of copper, we need to analyze the oxidation states of copper in each reaction. Reduction is defined as the gain of electrons or a decrease in oxidation state.

### Step-by-Step Solution:

1. **Identify the Oxidation States of Copper:**
- The oxidation state of copper in its elemental form (Cu) is 0.
- In compounds, the oxidation state can vary, typically +1 or +2.

2. **Analyze Each Reaction:**
- **Reaction 1:** Copper (Cu) is in solid form.
- Oxidation state: 0 (Cu) → +2 (Cu²⁺)
- Change: 0 to +2 indicates oxidation (loss of electrons).

- **Reaction 2:** Copper is in +2 oxidation state (Cu²⁺) and reacts with iodine (I⁻).
- Oxidation state: +2 (Cu²⁺) → +1 (Cu⁺)
- Change: +2 to +1 indicates reduction (gain of electrons).

- **Reaction 3:** Copper is in +2 oxidation state (Cu²⁺) and reacts with fluoride (F⁻).
- Oxidation state: +2 (Cu²⁺) → +2 (Cu²⁺)
- Change: No change, so neither oxidation nor reduction occurs.

- **Reaction 4:** Copper oxide (CuO) where Cu is +2 and reacts with hydroxide (OH⁻).
- Oxidation state: +2 (Cu²⁺) → +2 (Cu²⁺)
- Change: No change, so neither oxidation nor reduction occurs.

3. **Conclusion:**
- The only reaction that involves the reduction of copper is **Reaction 2**, where copper goes from +2 to +1, indicating a gain of electrons.

### Final Answer:
The reaction that involves the reduction of copper is **Reaction 2**.