The only metal which has a positive standard reductions potential in the first transition series is `"…................"`

Answer

To determine the only metal with a positive standard reduction potential in the first transition series, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the First Transition Series**:
The first transition series consists of the elements from Scandium (Sc, atomic number 21) to Zinc (Zn, atomic number 30). The elements are as follows:
- Scandium (Sc)
- Titanium (Ti)
- Vanadium (V)
- Chromium (Cr)
- Manganese (Mn)
- Iron (Fe)
- Cobalt (Co)
- Nickel (Ni)
- Copper (Cu)
- Zinc (Zn)

2. **Understand Standard Reduction Potential (SRP)**:
Standard reduction potential (E°) is a measure of the tendency of a chemical species to be reduced, which means to gain electrons. A positive E° value indicates a greater tendency to be reduced.

3. **Examine the Standard Reduction Potentials of the Metals**:
We need to look at the standard reduction potentials for the metals in the first transition series. Most of these metals have negative or zero standard reduction potentials.

4. **Identify Copper (Cu)**:
Among the metals in the first transition series, Copper (Cu) is known to have a positive standard reduction potential. The standard reduction potential for the half-reaction:
\[ Cu^{2+} + 2e^- \rightarrow Cu \]
is positive, indicating that copper ions are more likely to gain electrons and be reduced compared to the other metals in the series.

5. **Explain the Reason for Copper's Positive SRP**:
The positive standard reduction potential of copper can be attributed to its high atomization energy, which is greater than its hydration energy. This means that the energy required to separate copper atoms is higher than the energy released when copper ions are hydrated. As a result, the overall energy change favors the reduction of copper ions.

6. **Conclusion**:
Therefore, the only metal in the first transition series that has a positive standard reduction potential is Copper (Cu).

### Final Answer:
The only metal which has a positive standard reduction potential in the first transition series is **Copper (Cu)**.

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