Maximum paramagnetism in 3d series is shown by

Options

A. Mn
B. Co
C. Ni
D. Fe

Answer

To determine which element in the 3d series exhibits maximum paramagnetism, we need to analyze the number of unpaired electrons in the d-orbitals of each element. The more unpaired electrons an element has, the greater its paramagnetism.

### Step-by-Step Solution:

1. **Identify the Elements**: The elements in the 3d series that we need to consider are:
- Manganese (Mn)
- Cobalt (Co)
- Nickel (Ni)
- Iron (Fe)

2. **Determine Atomic Numbers and Electron Configurations**:
- **Manganese (Mn)**: Atomic number = 25
- Electron configuration: \( \text{[Ar]} 3d^5 4s^2 \)
- **Cobalt (Co)**: Atomic number = 27
- Electron configuration: \( \text{[Ar]} 3d^7 4s^2 \)
- **Nickel (Ni)**: Atomic number = 28
- Electron configuration: \( \text{[Ar]} 3d^8 4s^2 \)
- **Iron (Fe)**: Atomic number = 26
- Electron configuration: \( \text{[Ar]} 3d^6 4s^2 \)

3. **Count Unpaired Electrons**:
- **Manganese (Mn)**:
- Configuration: \( 3d^5 \)
- Unpaired electrons: 5 (all 5 electrons in the d-orbital are unpaired)
- **Cobalt (Co)**:
- Configuration: \( 3d^7 \)
- Unpaired electrons: 3 (the first five electrons fill singly, and the next two pair up)
- **Nickel (Ni)**:
- Configuration: \( 3d^8 \)
- Unpaired electrons: 2 (the first five fill singly, and the next three pair up)
- **Iron (Fe)**:
- Configuration: \( 3d^6 \)
- Unpaired electrons: 4 (the first five fill singly, and the sixth pairs up)

4. **Compare the Number of Unpaired Electrons**:
- Manganese: 5 unpaired electrons
- Cobalt: 3 unpaired electrons
- Nickel: 2 unpaired electrons
- Iron: 4 unpaired electrons

5. **Conclusion**:
- Manganese has the highest number of unpaired electrons (5), which means it exhibits the maximum paramagnetism among the elements considered.

### Final Answer:
**Manganese (Mn)** shows maximum paramagnetism in the 3d series.

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