The Phenomenon of sound propagation in air is

Explanation:

The phenomenon of sound propagation in air can be analyzed based on thermodynamic processes. There are several thermodynamic processes including isothermal, adiabatic, isobaric, and isochoric processes.

An isothermal process occurs at a constant temperature, an isobaric process occurs at a constant pressure, and an isochoric process occurs at a constant volume. However, sound propagation in air is best described by an adiabatic process.

An adiabatic process is one in which there is no exchange of heat with the surroundings. During the propagation of sound waves in air, the compression and rarefaction of air molecules happen so quickly that there is no time for heat exchange with the surroundings.

Thus, the correct answer is option 2, adiabatic process.