Energy conservation principle — identify the correct law “Energy can neither be created nor destroyed, but it can be transformed from one form to another.” This fundamental statement is known as:

Introduction / Context:
Every thermodynamic analysis begins with energy accounting. The principle that total energy is conserved while changing forms is the bedrock of engineering calculations in power plants, refrigeration, engines, and process equipment.

Given Data / Assumptions:

• Macroscopic (classical) thermodynamics framework.
• Energy transfer modes: heat and work.
• Systems may be closed or open; formulation adapts accordingly.

Concept / Approach:
The First Law of Thermodynamics expresses energy conservation. In a closed system, ΔE_system = Q_in − W_out. In a steady-flow open system (control volume), the rate form includes enthalpy flow and kinetic/potential energy changes but still conserves total energy. The law allows interconversion among forms (thermal, mechanical, electrical, chemical) without loss of total amount.

Step-by-Step Solution:
Identify the quoted statement: conservation with transformation allowed.Map to thermodynamic law: the First Law.Eliminate other options: Zeroth law (thermal equilibrium), Second law (direction/entropy), kinetic theory (microscopic model).

Verification / Alternative check:
Practical examples include electric heaters (work → heat), heat engines (heat → work), and generators (mechanical → electrical). All obey energy balance relationships.

Why Other Options Are Wrong:
Zeroth law defines temperature via equilibrium; second law sets limits on conversion efficiency; kinetic theory describes molecular behavior, not energy conservation law.

Common Pitfalls:
Assuming the First Law guarantees 100% heat-to-work conversion—this is restricted by the Second Law.

Final Answer:
First law of thermodynamics