When latent heat is added or removed from a substance, which of the following remains constant?

When latent heat is added or removed from a substance, the temperature remains constant during the phase change process. This phenomenon occurs because latent heat is the amount of energy required for a substance to change its state without changing its temperature. For example, when ice melts to become water, it absorbs heat (latent heat of fusion) without a change in temperature. Similarly, when water vapor condenses into liquid water, it releases latent heat while maintaining the same temperature.

This property is essential in processes like boiling and melting, where the substance transitions from one phase to another. During these transitions, any heat energy added or removed goes into changing the arrangement of the molecules, rather than increasing or decreasing the kinetic energy of the molecules, which would affect the temperature.

Other options, such as pressure, volume, and density, may change during these processes depending on the specific conditions of the substance, such as the external environment and the overall system's configuration.