Which of the following has maximum number of unpaired electrons ?

Options

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

Answer

To determine which of the given elements has the maximum number of unpaired electrons, we will analyze the electronic configurations of the provided options step by step.

### Step 1: Analyze Magnesium (Mg²⁺)
- **Atomic Number**: 12
- **Electronic Configuration**: 1s² 2s² 2p⁶ 3s²
- For Mg²⁺, we remove 2 electrons from the outermost shell (3s):
- **Mg²⁺ Configuration**: 1s² 2s² 2p⁶ 3s⁰
- **Unpaired Electrons**: 0 (All electrons are paired)

### Step 2: Analyze Boron (B³⁺)
- **Atomic Number**: 5
- **Electronic Configuration**: 1s² 2s² 2p¹
- For B³⁺, we remove 3 electrons (2 from 2s and 1 from 2p):
- **B³⁺ Configuration**: 1s² 2s⁰ 2p⁰
- **Unpaired Electrons**: 0 (All electrons are paired)

### Step 3: Analyze Vanadium (V³⁺)
- **Atomic Number**: 23
- **Electronic Configuration**: [Ar] 3d³ 4s²
- For V³⁺, we remove 3 electrons (2 from 4s and 1 from 3d):
- **V³⁺ Configuration**: [Ar] 3d² 4s⁰
- **Unpaired Electrons**: 2 (Both 3d electrons are unpaired)

### Step 4: Analyze Iron (Fe²⁺)
- **Atomic Number**: 26
- **Electronic Configuration**: [Ar] 3d⁶ 4s²
- For Fe²⁺, we remove 2 electrons (both from 4s):
- **Fe²⁺ Configuration**: [Ar] 3d⁶ 4s⁰
- **Unpaired Electrons**: 4 (In the 3d subshell, there are 4 unpaired electrons)

### Conclusion
After analyzing all the options:
- Mg²⁺: 0 unpaired electrons
- B³⁺: 0 unpaired electrons
- V³⁺: 2 unpaired electrons
- Fe²⁺: 4 unpaired electrons

**The element with the maximum number of unpaired electrons is Fe²⁺ with 4 unpaired electrons.**

### Final Answer
The correct option is **Fe²⁺**.

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