Which process is defined as no heat exchange?

Which process is defined as no heat exchange?

• A. Isothermal - constant volume
• B. Isobaric - constant pressure
• C. Isometric - constant volume
• D. Adiabatic - no heat exchange

Answer: (D)

No heat exchange defines an adiabatic process. When a system undergoes a change with Q = 0, the first law of thermodynamics says that the change in internal energy equals the negative of the work done by the system (ΔU = -W). For an ideal gas, this leads to characteristic state relationships like PV^γ = constant and TV^(γ-1) = constant, where γ is the ratio of Cp to Cv. The other descriptions imply heat transfer. If temperature stays constant (isothermal) while the gas expands or compresses, heat must flow in or out to counteract the work done, so Q ≠ 0. If pressure stays constant (isobaric) or volume stays constant (isometric/isochoric), maintaining those constraints generally requires heat exchange as the system performs work or absorbs energy. The term isometric isn’t the standard way to denote a specific heat-transfer condition, and it doesn’t inherently specify no heat exchange. So the process defined by no heat exchange is the adiabatic one.

No heat exchange defines an adiabatic process. When a system undergoes a change with Q = 0, the first law of thermodynamics says that the change in internal energy equals the negative of the work done by the system (ΔU = -W). For an ideal gas, this leads to characteristic state relationships like PV^γ = constant and TV^(γ-1) = constant, where γ is the ratio of Cp to Cv.

The other descriptions imply heat transfer. If temperature stays constant (isothermal) while the gas expands or compresses, heat must flow in or out to counteract the work done, so Q ≠ 0. If pressure stays constant (isobaric) or volume stays constant (isometric/isochoric), maintaining those constraints generally requires heat exchange as the system performs work or absorbs energy. The term isometric isn’t the standard way to denote a specific heat-transfer condition, and it doesn’t inherently specify no heat exchange. So the process defined by no heat exchange is the adiabatic one.