Thermodynamic terms – naming the region where a process occurs A defined quantity of matter or a region in space selected for analysis, within which a thermodynamic process takes place, is called a:

Introduction / Context:
Clear terminology is essential in thermodynamics. We must distinguish among system, surroundings, process, and cycle. This question asks you to identify the correct term for the “definite area or space” where analysis is focused and processes occur.

Given Data / Assumptions:

• A boundary separates the chosen entity from its surroundings.
• The entity can be a fixed mass (closed system) or a control volume (open system).
• Processes may involve heat and work interactions across the boundary.

Concept / Approach:
A thermodynamic system is the matter or region in space under study. When mass can cross the boundary it is called an open system or control volume; when mass is fixed it is a closed system. A process is the path between states, and a cycle is a sequence of processes returning to the initial state. The laws of thermodynamics provide the governing principles but are not “regions.”

Step-by-Step Solution:
Identify the phrase “definite area or space where a process takes place.”Map this to the term used in textbooks: system (including control volume as a system type).Therefore, the correct choice is “thermodynamic system.”

Verification / Alternative check:
Control-volume analyses of turbines, compressors, and nozzles treat the device interior region as the system. Piston–cylinder analyses treat the confined gas (fixed mass) as the system—consistent with the same overarching definition.

Why Other Options Are Wrong:

• Cycle: a closed sequence of processes, not the region.
• Process: the transformation between states, not the entity itself.
• Law: a governing principle, not a physical region.
• Control chart: unrelated term from quality management, not thermodynamics.

Common Pitfalls:
Using “control volume” and “system” as if mutually exclusive; in thermodynamics, a control volume is a type of system (open system).

Final Answer:
thermodynamic system