Question

The latent heat of evaporation of a substance is always
A. Greater than its latent heat of fusion
B. Greater than its latent heat of sublimation
C. Equal to its latent heat of sublimation
D. Less than its latent heat of fusion

Answer 1

Hint: Latent heat of vaporization is defined because the heat consumed or discharged when the matter gets disintegrated, changing the stage from fluid to gas stage at a consistent temperature.

Complete answer:
Latent heat is known as the heat or energy which is absorbed or released during a phase change of the substance. The change in phase can either be from a gas to a liquid to solid or vice versa. The latent heat is related to a property of heat known as enthalpy.
Latent heat is further classified in various types:
1) Latent heat of fusion: The latent heat of fusion is the heat consumed or discharged when a matter melts, changing the stage from a strong structure to fluid structure at a consistent temperature.
2) Latent heat of vaporization: The heat of vaporization is defined as the physical property of a substance and the heat required to change one mole of liquid at its boiling point under standard atmospheric pressure. In other words, it also can be stated that heat of vaporization is the heat consumed or discharged when matter disintegrates, changing stage from fluid to gas stage at a consistent temperature.
In the process of evaporation, the strong intermolecular force between the liquid molecules are broken in order to convert the liquid into vapor phase. So, more energy is needed to break the intermolecular attraction of the liquid molecules compared to just weakening the bonds in solid to convert it into liquid (during fusion).Thus, the latent heat of evaporation of a substance is always greater than its latent heat of fusion.

Hence, option (A) is the correct answer.

Note:
The latent heat of sublimation is defined as the energy required for converting a given quantity of solid into the vapor, without any change in temperature. The word latent means not very noticeable but existing. Thus latent heat is not visible but is present.