The correct option is **C. Diamagnetic materials**. ### Detailed Explanation **1. Understanding Magnetic Susceptibility:** Magnetic susceptibility (χ) is a measure of how much a material will become magnetized in an applied magnetic field. It indicates the degree of magnetization of a material in response to an external magnetic field. - **Positive Magnetic Susceptibility (χ > 0):** Materials with positive susceptibility are attracted to magnetic fields. This includes paramagnetic and ferromagnetic materials. - **Negative Magnetic Susceptibility (χ < 0):** Materials with negative susceptibility are repelled by magnetic fields. This is characteristic of diamagnetic materials. **2. Characteristics of Diamagnetic Materials:** Diamagnetic materials have a very weak and negative susceptibility. When placed in a magnetic field, they develop a very weak magnetic field in the opposite direction, causing them to be repelled. Common examples of diamagnetic materials include bismuth, copper, and graphite. **3. Why the Other Options Are Incorrect:** - **A. Ferrimagnetic materials:** - Ferrimagnetic materials have a positive magnetic susceptibility. They are characterized by having magnetic moments that align in opposite directions but are unequal, resulting in a net magnetic moment. They are attracted to magnetic fields, not repelled. - **B. Paramagnetic materials:** - Paramagnetic materials also have a positive magnetic susceptibility. They contain unpaired electrons that align with an external magnetic field, leading to a weak attraction. Examples include aluminum and platinum. - **D. Ferromagnetic materials:** - Ferromagnetic materials have a very high positive magnetic susceptibility. They can retain their magnetization even after the external magnetic field is removed. Common examples include iron, cobalt, and nickel. They are strongly attracted to magnetic fields. ### Summary of Key Concepts - **Magnetic Susceptibility (χ):** Indicates how a material responds to a magnetic field (positive = attracted, negative = repelled). - **Diamagnetic Materials:** Characterized by negative susceptibility, weakly repelled by magnetic fields. - **Ferrimagnetic and Ferromagnetic Materials:** Both have positive susceptibility and are attracted to magnetic fields. - **Paramagnetic Materials:** Also have positive susceptibility and are weakly attracted to magnetic fields. ### Revision Summary - **Diamagnetic materials** are characterized by **negative magnetic susceptibility** and are **repelled** by magnetic fields. - **Ferrimagnetic** and **ferromagnetic materials** have **positive susceptibility** and are **attracted** to magnetic fields. - **Paramagnetic materials** have **weak positive susceptibility** and are **weakly attracted** to magnetic fields. - Remember that **only diamagnetic materials** exhibit the property of being repelled by a magnetic field.