No-heat-transfer processes A process in which the working substance neither receives nor rejects heat to the surroundings during compression or expansion is called:

Introduction / Context:
Thermodynamic processes are often idealized by constraints on heat transfer or temperature. This question asks you to name the process that proceeds with zero heat exchange between the system and its surroundings.

Given Data / Assumptions:

• No heat crosses the boundary: Q = 0 during the process.
• Compression or expansion of a gas is implied.
• Work interactions may still occur.

Concept / Approach:
When Q = 0 for the entire process, it is termed adiabatic. If, in addition, the process is reversible, it is isentropic; however, the term “adiabatic” alone specifies only the heat-transfer condition. An isothermal process, by contrast, maintains constant temperature and generally requires heat transfer to offset compression/expansion work.

Step-by-Step Solution:
Apply the first law in differential form: δQ = dU + δW.Set δQ = 0 for an adiabatic process → dU = −δW (internal energy change balances boundary work).Therefore, the correct name for the process is “adiabatic process.”

Verification / Alternative check:
In rapid (well-insulated) compressions, temperature rises because work is converted to internal energy without heat rejection—classic adiabatic behavior observed in compression-ignition engines.

Why Other Options Are Wrong:

• Isothermal requires heat exchange to maintain constant temperature during volume change.
• “Polytropic with n = 1” is isothermal for ideal gases, not adiabatic.
• “Hyperbolic process” is an older term for p * V = constant (isothermal).
• Isobaric maintains pressure, not heat flow.

Common Pitfalls:
Equating “adiabatic” with “isentropic” unconditionally; irreversibilities make many adiabatic processes non-isentropic.

Final Answer:
adiabatic process