Q1: Lubricants can be used to

ANS:D - all (a), (b) & (c).

1. Transmit power hydraulically: Lubricants are commonly used in hydraulic systems to transmit power. Hydraulic systems use pressurized fluid (usually oil-based lubricants) to generate and transmit force, allowing for the operation of various machinery and equipment such as hydraulic cylinders, motors, and actuators. The lubricant serves as the working fluid within the hydraulic system, facilitating the transfer of force from one component to another.
2. Form a seal in compressors: Lubricants are essential in compressors to form a seal between moving parts and to provide lubrication for the compression process. Compressors are mechanical devices used to increase the pressure of a gas by reducing its volume. Lubricants are used to reduce friction and wear between the moving components of the compressor, such as pistons, valves, and bearings, while also forming a seal to prevent gas leakage during compression.
3. Remove contaminants by flushing and to insulate transformers, switchgears etc.: Lubricants can also be used for cleaning purposes by flushing out contaminants from machinery and equipment. In certain applications, lubricants are used as flushing agents to remove dirt, debris, and other contaminants from mechanical systems, ensuring optimal performance and longevity. Additionally, lubricants are used as insulating fluids in transformers and switchgears to provide electrical insulation and cooling.
4. All of the above (a), (b), & (c): Based on the explanations provided, lubricants can indeed be used for all the mentioned purposes:
   • Transmitting power hydraulically in hydraulic systems.
   • Forming seals and providing lubrication in compressors.
   • Removing contaminants by flushing and providing insulation in transformers, switchgears, and other electrical equipment.