Which of the following materials is rarely used as dielectric material in power cables? 

Explanation:

• Gases are rarely used as dielectric materials in power cables. In power cables, dielectric materials are used to insulate and separate conductors, preventing electrical leakage and ensuring the efficient transmission of electrical energy.
• While liquids, solids, and compound materials are commonly employed as dielectrics in power cables, gases are not commonly used due to their lower dielectric strength compared to other materials.
• Gases can, however, be found in certain specialized applications, such as gas-insulated transmission lines, but they are not as prevalent as solid, liquid, or compound dielectrics in typical power cable designs.