Latent heat is defined as heat absorbed or released during which process?

Latent heat refers to the heat energy that is absorbed or released by a substance during a phase change, without a change in temperature. This process occurs, for example, when a solid melts into a liquid (melting) or when a liquid vaporizes into a gas (evaporation). During these phase changes, the energy is used to alter the molecular structure of the substance rather than to increase its temperature.

For instance, when ice melts to become water, it absorbs latent heat; conversely, when water freezes into ice, it releases latent heat. Similarly, when water evaporates, it absorbs heat from the environment, while condensation involves the release of latent heat. Thus, the key characteristic of latent heat is that it is associated with these phase transitions rather than simply raising or lowering the temperature of a substance.

In contrast, heating up or cooling down options would not involve a phase change; they refer to temperature changes without altering the physical state of a material. The option focusing solely on evaporation does not encompass all phase changes, such as melting or freezing, which are crucial to the definition of latent heat. Therefore, the definition of latent heat is accurately captured by its association with phase changes.