Which one of the following is a non-magneticsubstance?

Options

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

Answer

To determine which of the given substances is non-magnetic, we can analyze each option based on their magnetic properties.

### Step-by-Step Solution:

1. **Identify the Options**: The options provided are:
- a) Iron
- b) Nickel
- c) Cobalt
- d) Brass

2. **Understand Magnetic Properties**:
- **Ferromagnetic Substances**: These materials have a positive magnetic susceptibility (χm > 0) and can be magnetized. Examples include iron, nickel, and cobalt.
- **Non-Magnetic Substances**: These materials have a negative or very low magnetic susceptibility (χm < 0) and do not exhibit significant magnetic properties.

3. **Analyze Each Option**:
- **Iron**: A well-known ferromagnetic material. It has a positive magnetic susceptibility.
- **Nickel**: Another ferromagnetic material with positive magnetic susceptibility.
- **Cobalt**: Also a ferromagnetic material with positive magnetic susceptibility.
- **Brass**: An alloy made primarily of copper and zinc, which is not ferromagnetic. It has a negative magnetic susceptibility.

4. **Conclusion**: Since iron, nickel, and cobalt are all ferromagnetic substances, the only non-magnetic substance among the options is brass.

5. **Final Answer**: The correct option is **d) Brass**.