What type of heat is required to raise the temperature of a unit mass of a substance by 1 degree Celsius without changing its state?

The correct answer is that the type of heat required to raise the temperature of a unit mass of a substance by 1 degree Celsius without changing its state is referred to as "sensible heat." This term is used to describe the heat energy that causes a measurable temperature change in a substance. When sensible heat is applied to a substance, it affects the kinetic energy of the molecules, leading to an increase in temperature, while the state of the substance (solid, liquid, or gas) remains unchanged.

"Sensible heat" is differentiated from "latent heat," which is associated with the phase changes of a substance, where the temperature remains constant during transitions such as melting or boiling. "Specific heat" pertains to the amount of sensible heat per unit mass required to raise the temperature of a substance by one degree Celsius; however, it is not itself the type of heat being described in the question. "Saturated" generally refers to a state of a substance at a particular temperature and pressure where it is in equilibrium between phases, which does not denote the direct heating effect as in sensible heat.

Understanding these distinctions is crucial for comprehending thermal processes in power engineering and other related fields.