Which statement best describes the first law of thermodynamics?

The first law of thermodynamics, often referred to as the law of energy conservation, asserts that energy cannot be created or destroyed; rather, it can only be transformed from one form to another or transferred from one system to another. This principle underlines the idea that the total energy of an isolated system remains constant, although it may change states (for example, from kinetic to potential energy, or from thermal energy to mechanical work).

Understanding this law is crucial when studying thermodynamic systems, especially in refrigeration and heat transfer processes. For instance, in a refrigeration cycle, electrical energy is converted into work, which in turn facilitates the transfer of heat from a lower temperature body to a higher temperature body—illustrating energy transformation rather than creation or destruction.

The other statements do not align with this fundamental concept. For example, claiming that energy can be created from nothing contradicts the foundational principles of thermodynamics, while suggesting that energy can be destroyed also misrepresents the conservation law. Additionally, the assertion that energy is always wasted in thermodynamic processes could imply inefficiencies, which is more about practical energy losses rather than a failure of the conservation principle itself.