Which of the following species has (have) five unpaired electron ?

Options

A. Cs
B. Mn
C. `Mn^(2+)`
D. `Fe^(2+)`

Explanation

To determine which species have five unpaired electrons, we will analyze the electronic configurations of the given elements and ions.

### Step 1: Analyze Cesium (Cs)
- **Atomic Number**: 55
- **Electronic Configuration**: [Xe] 6s¹
- **Unpaired Electrons**:
- The configuration shows that cesium has one electron in the 6s orbital.
- Therefore, **Cesium has 1 unpaired electron**.

### Step 2: Analyze Manganese (Mn)
- **Atomic Number**: 25
- **Electronic Configuration**: [Ar] 4s² 3d⁵
- **Unpaired Electrons**:
- The 3d subshell has 5 electrons, and according to Hund's rule, all 5 electrons will occupy different orbitals before pairing occurs.
- Therefore, **Manganese has 5 unpaired electrons**.

### Step 3: Analyze Manganese Ion (Mn²⁺)
- **Electronic Configuration**: When manganese loses 2 electrons, it loses them from the 4s orbital first.
- **Configuration of Mn²⁺**: [Ar] 3d⁵
- **Unpaired Electrons**:
- Similar to neutral manganese, the 3d subshell has 5 electrons, all unpaired.
- Therefore, **Mn²⁺ also has 5 unpaired electrons**.

### Step 4: Analyze Iron Ion (Fe²⁺)
- **Atomic Number**: 26
- **Electronic Configuration**: [Ar] 4s² 3d⁶
- **Unpaired Electrons**:
- For Fe²⁺, we remove 2 electrons from the 4s orbital first.
- The configuration for Fe²⁺ is [Ar] 3d⁶.
- In the 3d subshell, there are 6 electrons. According to Hund's rule, 4 of these will be unpaired, and 2 will be paired.
- Therefore, **Fe²⁺ has 4 unpaired electrons**.

### Conclusion
From the analysis:
- **Cesium (Cs)**: 1 unpaired electron
- **Manganese (Mn)**: 5 unpaired electrons
- **Manganese Ion (Mn²⁺)**: 5 unpaired electrons
- **Iron Ion (Fe²⁺)**: 4 unpaired electrons

Thus, the species that have five unpaired electrons are **Manganese (Mn) and Manganese Ion (Mn²⁺)**.

### Final Answer
**Manganese (Mn) and Manganese Ion (Mn²⁺) have five unpaired electrons.**

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