The concept of internal energy is derived from which law of thermodynamics?

The concept of internal energy is fundamentally derived from the first law of thermodynamics, which is also known as the law of energy conservation. This law states that energy cannot be created or destroyed, only transformed from one form to another within a closed system. Internal energy refers to the total energy contained within a system, encompassing both the kinetic energy of particles and the potential energy arising from intermolecular forces. The first law of thermodynamics provides a comprehensive framework for understanding how energy is stored, transferred, and conserved within a system. It articulates that the change in internal energy of a system is equal to the heat added to the system minus the work done by the system on its surroundings. This foundational principle is crucial for analyzing thermodynamic processes and systems in various scientific and engineering applications. Therefore, the correct answer is [B] First law.