For which of the following metal `M^(2+)(aq) +2e^- to M (s)` reaction have positive reduction potential value

Options

A. Fe
B. Cu
C. Zn
D. Al

Answer

To determine which metal \( M^{2+} + 2e^- \rightarrow M \) has a positive reduction potential value, we can follow these steps:

### Step 1: Understand the Concept of Reduction Potential
Reduction potential is a measure of the tendency of a chemical species to acquire electrons and thereby be reduced. A positive reduction potential indicates a greater tendency to gain electrons.

### Step 2: Refer to the Electrochemical Series
The electrochemical series ranks metals based on their standard reduction potentials. Metals that are higher in the series have a greater tendency to be reduced (gain electrons) and thus have positive reduction potentials. Conversely, metals lower in the series tend to lose electrons and have negative reduction potentials.

### Step 3: Identify the Metals in the Question
The metals given in the question are:
- Iron (Fe)
- Copper (Cu)
- Zinc (Zn)
- Aluminum (Al)

### Step 4: Locate the Metals in the Electrochemical Series
In the electrochemical series:
- Copper (Cu) is above hydrogen and has a positive reduction potential.
- Iron (Fe), Zinc (Zn), and Aluminum (Al) are below hydrogen and have negative reduction potentials.

### Step 5: Conclusion
From the electrochemical series, we can conclude that:
- **Copper (Cu)** is the only metal among the given options that has a positive reduction potential value.

### Final Answer
The metal that has a positive reduction potential value for the reaction \( M^{2+} + 2e^- \rightarrow M \) is **Copper (Cu)**.

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