Question 559Steam Plants - Assistant Engineer

The correct answer is C) expands in volume. As steam passes through an engine or turbine, it expands in volume, causing its pressure to decrease. This is in accordance with the principles of thermodynamics, specifically Boyle's law, which states that as the volume of a gas increases, its pressure decreases, assuming temperature remains constant. The other options are incorrect: A) becomes saturated again - Saturation refers to the state where the steam is in equilibrium with its liquid phase, which is not the relevant process here. B) diminishes in volume - The opposite of the correct answer, as the steam expands in volume. D) becomes superheated again - Superheating refers to heating the steam beyond its saturation point, which is not the process occurring in an engine or turbine.