The Joule-Thomson process is a thermodynamic process that involves the expansion of a gas between two states at different temperatures and pressures. It is commonly used for attaining low temperatures in refrigeration and liquefaction applications.

Option 1: An isobaric process is a process that takes place at constant pressure. In the case of the Joule-Thomson process, the pressure changes since the gas expands, so it is not considered isobaric.

Option 2: An isoenthalpic process is a process that takes place at constant enthalpy. In the Joule-Thomson process, the enthalpy remains constant due to it being a reversible and adiabatic process. This makes option 2 correct.

Option 3: An adiabatic process is a process that takes place without any heat exchange with the surroundings. In the Joule-Thomson process, the expansion is adiabatic, but it is not the defining characteristic of the process. So, while adiabatic conditions apply to the process, it is not solely an adiabatic process.

Option 4: An isochoric process is a process that takes place at constant volume. In the Joule-Thomson process, the volume