Which of the following is not a magnetic material?

Options

A. gold
B. nickel
C. iron
D. cobalt

Answer

To determine which of the given materials is not a magnetic material, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Materials**: The materials provided in the question are gold, nickel, iron, and cobalt.

2. **Understand Magnetic Materials**: Magnetic materials are those that are attracted to magnets or can be magnetized themselves. Common examples include iron, nickel, and cobalt.

3. **Identify Non-Magnetic Materials**: Non-magnetic materials are not attracted to magnets and cannot be magnetized. Examples of non-magnetic materials include gold, plastic, and paper.

4. **Analyze Each Material**:
- **Nickel**: This is a magnetic material.
- **Iron**: This is also a magnetic material.
- **Cobalt**: This is another magnetic material.
- **Gold**: This is not a magnetic material.

5. **Conclusion**: Since gold is not attracted to magnets and cannot be magnetized, it is the non-magnetic material among the options provided.

### Final Answer:
The material that is not a magnetic material is **gold**.

---