Which of the following gaseous ion contains maximum number of unpaired electrons?

Options

A. `Fe^(2+)`
B. `Co^(3+)`
C. `Co^(2+)`
D. `Fe^(3+)`

Explanation

To determine which of the given gaseous ions contains the maximum number of unpaired electrons, we will analyze each ion step by step.

### Step 1: Identify the ions and their electronic configurations
We have the following ions to analyze:
1. Fe²⁺
2. Co³⁺
3. Co²⁺
4. Fe³⁺

### Step 2: Determine the atomic numbers
- Iron (Fe) has an atomic number of 26.
- Cobalt (Co) has an atomic number of 27.

### Step 3: Write the electronic configurations
- The general electronic configuration for Fe is:
- Fe: [Ar] 4s² 3d⁶
- The general electronic configuration for Co is:
- Co: [Ar] 4s² 3d⁷

### Step 4: Calculate the electronic configurations for the ions
1. **Fe²⁺**:
- Remove 2 electrons (from 4s):
- Configuration: 3d⁶
2. **Co³⁺**:
- Remove 3 electrons (2 from 4s and 1 from 3d):
- Configuration: 3d⁶
3. **Co²⁺**:
- Remove 2 electrons (from 4s):
- Configuration: 3d⁷
4. **Fe³⁺**:
- Remove 3 electrons (2 from 4s and 1 from 3d):
- Configuration: 3d⁵

### Step 5: Fill the d-orbitals and count unpaired electrons
1. **Fe²⁺ (3d⁶)**:
- Filling order: ↑↓ ↑↓ ↑ ↑ ↑
- Unpaired electrons: 4

2. **Co³⁺ (3d⁶)**:
- Filling order: ↑↓ ↑↓ ↑ ↑ ↑
- Unpaired electrons: 4

3. **Co²⁺ (3d⁷)**:
- Filling order: ↑↓ ↑↓ ↑ ↑ ↑ ↑
- Unpaired electrons: 3

4. **Fe³⁺ (3d⁵)**:
- Filling order: ↑ ↑ ↑ ↑ ↑
- Unpaired electrons: 5

### Step 6: Compare the number of unpaired electrons
- Fe²⁺: 4 unpaired electrons
- Co³⁺: 4 unpaired electrons
- Co²⁺: 3 unpaired electrons
- Fe³⁺: 5 unpaired electrons

### Conclusion
The ion with the maximum number of unpaired electrons is **Fe³⁺**, which has **5 unpaired electrons**.

### Final Answer
**Fe³⁺ contains the maximum number of unpaired electrons (5).**

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