Which will reduce zinc oxide to zinc?

Options

A. Mg
B. Pb
C. CU
D. Fe

Explanation

To determine which metal can reduce zinc oxide (ZnO) to zinc (Zn), we need to analyze the reduction potentials of the metals provided in the options. Here’s a step-by-step solution:

### Step 1: Understand the Reduction Reaction
The reduction of zinc oxide to zinc can be represented as:
\[ \text{ZnO} + 2e^- \rightarrow \text{Zn} + \text{O}^{2-} \]
In this reaction, zinc is being reduced from its +2 oxidation state in ZnO to its 0 oxidation state in Zn.

### Step 2: Identify the Reduction Potentials
We need to know the standard reduction potentials (E°) for the metals provided in the options:
1. **Magnesium (Mg)**:
\[ \text{Mg}^{2+} + 2e^- \rightarrow \text{Mg} \quad E° = -2.36 \, \text{V} \]
2. **Lead (Pb)**:
\[ \text{Pb}^{2+} + 2e^- \rightarrow \text{Pb} \quad E° = -0.13 \, \text{V} \]
3. **Copper (Cu)**:
\[ \text{Cu}^{2+} + 2e^- \rightarrow \text{Cu} \quad E° = +0.34 \, \text{V} \]
4. **Iron (Fe)**:
\[ \text{Fe}^{2+} + 2e^- \rightarrow \text{Fe} \quad E° = -0.44 \, \text{V} \]

### Step 3: Compare with Zinc's Reduction Potential
The reduction potential of zinc is:
\[ \text{Zn}^{2+} + 2e^- \rightarrow \text{Zn} \quad E° = -0.76 \, \text{V} \]

### Step 4: Determine Which Metal Can Reduce ZnO
For a metal to reduce ZnO to Zn, it must have a higher (less negative or more positive) reduction potential than that of zinc (-0.76 V).

- **Magnesium**: -2.36 V (less than -0.76 V)
- **Lead**: -0.13 V (greater than -0.76 V)
- **Copper**: +0.34 V (greater than -0.76 V)
- **Iron**: -0.44 V (less than -0.76 V)

### Step 5: Conclusion
The metals that can reduce zinc oxide to zinc must have a reduction potential greater than -0.76 V. From our analysis, both lead and copper have higher reduction potentials than zinc. However, magnesium and iron do not.

### Final Answer
The metals that can reduce zinc oxide to zinc are **Lead (Pb)** and **Copper (Cu)**. However, if we are to select the most effective reducing agent, **Copper (Cu)** is the strongest reducing agent among the options provided.