ANS:D - latent heat

The quantity of heat required to evaporate 1 kg of a saturated liquid is called the "latent heat" or "heat of vaporization." This term refers to the amount of heat energy absorbed by a substance during the phase transition from liquid to vapor at constant temperature and pressure. So, the correct option is: latent heat Latent heat is the amount of heat energy absorbed or released by a substance during a phase change, such as melting, freezing, vaporization, or condensation, without a change in temperature. It represents the energy required to overcome the intermolecular forces holding the particles together in a particular phase or to break these forces when transitioning between phases. There are two main types of latent heat:

1. Latent Heat of Fusion: This is the heat energy absorbed or released when a substance changes between solid and liquid states, or vice versa, at its melting or freezing point. When a solid is heated to its melting point, it absorbs latent heat to break the bonds holding its molecules together, transitioning into a liquid. Conversely, when a liquid is cooled to its freezing point, it releases latent heat as it solidifies and bonds form between its molecules.
2. Latent Heat of Vaporization: This is the heat energy absorbed or released when a substance changes between liquid and vapor states, or vice versa, at its boiling or condensation point. When a liquid is heated to its boiling point, it absorbs latent heat to overcome intermolecular forces and transition into a vapor. Conversely, when a vapor is cooled to its condensation point, it releases latent heat as it condenses into a liquid.

Latent heat is essential in various natural phenomena and technological applications. For example, it plays a crucial role in weather patterns, such as the formation of clouds and precipitation, where water vapor condenses into liquid droplets, releasing latent heat into the atmosphere. In industries such as refrigeration and air conditioning,