In which of the following pairs, the outer most electronic configuration will be the same?

Options

A. `Cr^+ and Mn^(2+)`
B. `Ni^(2+) and Cu^+`
C. `Fe^(2+) and Co^+`
D. `V^(2+) and Cr^+`

Answer

To determine which pairs of species have the same outermost electronic configuration, we need to analyze the electronic configurations of the given elements and their ions. Here’s a step-by-step breakdown:

### Step 1: Identify the atomic numbers and electronic configurations of the elements
1. **Chromium (Cr)**: Atomic number = 24
- Electronic configuration: Argon (Ar) 3d⁵ 4s¹
2. **Vanadium (V)**: Atomic number = 23
- Electronic configuration: Ar 3d³ 4s²
3. **Copper (Cu)**: Atomic number = 29
- Electronic configuration: Ar 3d¹⁰ 4s¹
4. **Nickel (Ni)**: Atomic number = 28
- Electronic configuration: Ar 3d⁸ 4s²
5. **Iron (Fe)**: Atomic number = 26
- Electronic configuration: Ar 3d⁶ 4s²
6. **Cobalt (Co)**: Atomic number = 27
- Electronic configuration: Ar 3d⁷ 4s²
7. **Manganese (Mn)**: Atomic number = 25
- Electronic configuration: Ar 3d⁵ 4s²

### Step 2: Write the electronic configurations of the ions
1. **Cr³⁺**:
- Remove 1 electron from 4s and 2 from 3d:
- Configuration: Ar 3d⁵
2. **V²⁺**:
- Remove 2 electrons from 4s:
- Configuration: Ar 3d³
3. **Cu²⁺**:
- Remove 1 electron from 4s and 1 from 3d:
- Configuration: Ar 3d⁹
4. **Ni²⁺**:
- Remove 2 electrons from 4s:
- Configuration: Ar 3d⁸
5. **Fe³⁺**:
- Remove 2 electrons from 4s and 1 from 3d:
- Configuration: Ar 3d⁵
6. **Co²⁺**:
- Remove 2 electrons from 4s:
- Configuration: Ar 3d⁷
7. **Mn²⁺**:
- Remove 2 electrons from 4s:
- Configuration: Ar 3d⁵

### Step 3: Compare the outermost electronic configurations
- **Cr³⁺**: Ar 3d⁵
- **V²⁺**: Ar 3d³
- **Cu²⁺**: Ar 3d⁹
- **Ni²⁺**: Ar 3d⁸
- **Fe³⁺**: Ar 3d⁵
- **Co²⁺**: Ar 3d⁷
- **Mn²⁺**: Ar 3d⁵

### Step 4: Identify pairs with the same configuration
From the configurations:
- **Cr³⁺** (Ar 3d⁵) has the same configuration as **Fe³⁺** (Ar 3d⁵) and **Mn²⁺** (Ar 3d⁵).

### Conclusion
The pairs with the same outermost electronic configuration are:
- Cr³⁺ and Fe³⁺
- Cr³⁺ and Mn²⁺
- Fe³⁺ and Mn²⁺