Which of the following is not a ferromagnetic substance

Options

A. Cobalt
B. Nickel
C. Manganese
D. Iron

Explanation

To determine which of the given substances is not a ferromagnetic substance, we need to understand the characteristics of ferromagnetic materials.

### Step-by-Step Solution:

1. **Define Ferromagnetism**:
- Ferromagnetic substances are materials that can be magnetized; they have a strong attraction to magnetic fields and can retain their magnetic properties even after the external magnetic field is removed. Common examples include iron, cobalt, and nickel.

2. **Identify the Options**:
- The options provided are:
- Option 1: Cobalt
- Option 2: Nickel
- Option 3: Manganese
- Option 4: Iron

3. **Analyze Each Option**:
- **Cobalt**: This is a well-known ferromagnetic material.
- **Nickel**: Another common ferromagnetic material.
- **Manganese**: Manganese is generally considered to be antiferromagnetic or paramagnetic, depending on its allotrope and conditions, and does not exhibit ferromagnetism in the same way as iron, cobalt, and nickel.
- **Iron**: This is one of the most recognized ferromagnetic materials.

4. **Conclusion**:
- Among the options, manganese is not a ferromagnetic substance. Therefore, the correct answer is **Option 3: Manganese**.

### Final Answer:
Manganese is not a ferromagnetic substance.

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