Which cycle process involves no loss or gain of heat?

Which cycle process involves no loss or gain of heat?

• A. Adiabatic Process
• B. Isothermal Process
• C. Isobaric Process
• D. Isentropic Process

Answer: (A)

Heat transfer is zero in an adiabatic process. In the energy balance form ΔU = Q − W (using the common convention that heat added to the system is positive and work done by the system is positive), setting Q = 0 means the change in internal energy comes solely from work. For a cycle, you end where you started, so the total ΔU over the cycle is zero; with no heat exchanged, the total work over the cycle must also sum to zero. That’s why this cycle process is described as involving no loss or gain of heat. The other processes involve heat transfer: keeping temperature constant requires heat flow to compensate for volume changes, maintaining constant pressure generally involves heat exchange, and constant entropy describes a path where entropy does not change (a reversible adiabatic path is a special case, but the explicit definition tied to zero heat transfer points to the adiabatic type).

Heat transfer is zero in an adiabatic process. In the energy balance form ΔU = Q − W (using the common convention that heat added to the system is positive and work done by the system is positive), setting Q = 0 means the change in internal energy comes solely from work. For a cycle, you end where you started, so the total ΔU over the cycle is zero; with no heat exchanged, the total work over the cycle must also sum to zero. That’s why this cycle process is described as involving no loss or gain of heat. The other processes involve heat transfer: keeping temperature constant requires heat flow to compensate for volume changes, maintaining constant pressure generally involves heat exchange, and constant entropy describes a path where entropy does not change (a reversible adiabatic path is a special case, but the explicit definition tied to zero heat transfer points to the adiabatic type).