Four successive members of the first row transition elements are listed below with atomic numbers. Which one of them is expected to have the highest `E_(M^(3+)//M^(2+))^(0)` value

Options

A. `Cr(Z=24)`
B. `Mn(Z=25)`
C. `Fe(Z=26)`
D. `Co(Z=27)`

Explanation

To determine which of the four successive members of the first row transition elements has the highest \( E^{\circ}(M^{3+}/M^{2+}) \) value, we can follow these steps:

### Step 1: Identify the Transition Elements
The first row transition elements include Scandium (Sc, Z=21), Titanium (Ti, Z=22), Vanadium (V, Z=23), Chromium (Cr, Z=24), Manganese (Mn, Z=25), Iron (Fe, Z=26), Cobalt (Co, Z=27), Nickel (Ni, Z=28), and Copper (Cu, Z=29). We need to focus on four successive members.

### Step 2: Select Four Successive Members
Let's select Chromium (Cr), Manganese (Mn), Iron (Fe), and Cobalt (Co) for our analysis. Their atomic numbers are:
- Chromium (Cr, Z=24)
- Manganese (Mn, Z=25)
- Iron (Fe, Z=26)
- Cobalt (Co, Z=27)

### Step 3: Understand the \( E^{\circ} \) Values
The standard reduction potential \( E^{\circ}(M^{3+}/M^{2+}) \) values for these elements are as follows:
- Chromium: \( E^{\circ}(Cr^{3+}/Cr^{2+}) = -0.41 \, V \)
- Manganese: \( E^{\circ}(Mn^{3+}/Mn^{2+}) = +1.57 \, V \)
- Iron: \( E^{\circ}(Fe^{3+}/Fe^{2+}) = +0.77 \, V \)
- Cobalt: \( E^{\circ}(Co^{3+}/Co^{2+}) = +1.97 \, V \)

### Step 4: Compare the \( E^{\circ} \) Values
Now we compare the \( E^{\circ} \) values:
- Chromium: -0.41 V
- Manganese: +1.57 V
- Iron: +0.77 V
- Cobalt: +1.97 V

### Step 5: Identify the Highest Value
From the comparison, we can see that Cobalt has the highest \( E^{\circ}(Co^{3+}/Co^{2+}) = +1.97 \, V \).

### Conclusion
Thus, the element among the four successive members of the first row transition elements that is expected to have the highest \( E^{\circ}(M^{3+}/M^{2+}) \) value is **Cobalt (Co)**.

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