Question

which best describes a characteristic of an adiabatic process? heat is absorbed but not released by the system. all heat added to the system is transformed into work. there is a gradual shift between compression and expansion of a gas. when gas is compressed in the system, temperature remains constant.

Explanation:

In an adiabatic process, there is no heat transfer between the system and its surroundings ($Q = 0$). According to the first - law of thermodynamics $\Delta U=Q - W$. Since $Q = 0$, any change in internal energy of the system is due to work done on or by the system. So all heat added (in the form of work input or output) is transformed into work. The other options are incorrect: heat is neither absorbed nor released in an adiabatic process; the shift between compression and expansion is not the defining characteristic; and it is an isothermal process where temperature remains constant during gas compression/expansion, not an adiabatic one.

Answer:

All heat added to the system is transformed into work.