200 J of work is done in compressing a gas adiabatically. What is the change in internal energy of the gas?

According to the second law of thermodynamics, for any process that may occur within an isolated system, which one of the choices applies?

The coefficient of performance (COP) of a refrigerator is defined as the ratio of:

A solid X is in thermal equilibrium with a solid Y, which is at the same temperature as a third solid Z. The three bodies are of different materials and masses. Which one of the following statements is certainly correct?

Is it possible to transfer heat from a cold reservoir to a hot reservoir?