Thermodynamic process naming – constant-temperature transformation A process in which the temperature of the working substance remains strictly constant during expansion or compression is called:

Introduction / Context:
Naming thermodynamic processes by the variable held constant is foundational. Here, the temperature remains constant while the system expands or compresses.

Given Data / Assumptions:

• Temperature is maintained constant for the entire process.
• Working substance may be ideal gas for simple relations.
• Quasi-equilibrium path is implied for clear property relations.

Concept / Approach:
Isothermal means constant temperature. For an ideal gas, the equation of state gives p * v = constant at fixed T, which traces a rectangular hyperbola on a p–v diagram (hence sometimes termed a hyperbolic curve).

Step-by-Step Solution:
Identify the controlled variable: temperature remains constant.Relate to ideal-gas law: p * v = m * R * T = constant for fixed m and T.Conclude: the correct name is isothermal process.

Verification / Alternative check:
Work for an ideal-gas isothermal process: W = m * R * T * ln(V2/V1), consistent with constant T behavior.

Why Other Options Are Wrong:

• Hyperbolic process: describes the p–v curve shape but does not explicitly state temperature constancy for non-ideal substances.
• Adiabatic: no heat transfer, temperature generally changes.
• Polytropic: general law p * v^n = constant; does not enforce constant T unless n = 1 for ideal gases.
• Isobaric: constant pressure, not constant temperature.

Common Pitfalls:
Assuming “hyperbolic” always means isothermal—even though many non-ideal behaviors deviate.

Final Answer:
isothermal process