Extensive property definition (thermodynamics): In the context of properties of a system, what is true about an extensive property?

Introduction / Context:
Thermodynamic properties are categorized as intensive or extensive. This classification is fundamental for formulating balances, scaling systems, and interpreting property tables. The wording in some options can be misleading, so it is important to rely on the precise definition.

Given Data / Assumptions:

• Extensive properties depend on the size or mass of the system.
• Examples: mass, volume, total energy, total entropy, total internal energy.
• Intensive properties are independent of system size (e.g., temperature, pressure, density).

Concept / Approach:
An extensive property doubles when the system size is doubled at the same state. None of the listed options A–C are proper definitions; they misuse process words (heat transferred, work done, energy utilized) instead of property words. Heat and work are path functions, not properties, and “utilised” is not a property concept. Therefore, the only correct choice among those provided is “none of these.”

Step-by-Step Solution:

Verification / Alternative check:
Doubling a system: two identical tanks each with mass m and volume V together have mass 2m and volume 2V, confirming mass and volume are extensive.

Why Other Options Are Wrong:

• Heat/work “transferred/done”: Not properties; they are path-dependent interactions, not state descriptors.
• “Energy utilised”: Vague process description, not a property.

Common Pitfalls:
Confusing properties (state functions) with interactions (path functions); assuming “energy” alone must be intensive—note that total energy is extensive while specific energy (per mass) is intensive.

Final Answer:
none of these