Which equation represents the first law of thermodynamics?

The first law of thermodynamics is fundamentally concerned with the conservation of energy within a closed system. It states that the change in internal energy (ΔU) of a system is equal to the heat added to the system (Q) minus the work done by the system (W). This relationship emphasizes the balance between energy input and output, illustrating that energy cannot be created or destroyed, only transformed from one form to another.

In the correct equation, ΔU represents the change in internal energy, Q indicates the heat added to the system, and W denotes work done by the system. This equation succinctly encapsulates the essence of energy transfer and conservation, making it the cornerstone of thermodynamic principles.