Consider the following statements : 1. Steam at 100° C and boiling water at 100° C contain same amount of heat. 2. Latent heat of fusion of ice is equal to the latent heat of vaporization of water. 3. In an air-conditioner, heat is extracted from the room-air at the evaporator coils and is rejected out at the condenser coils. Which of these statements is/are correct?

Statement 1 is false: although both steam and boiling water are at 100 °C, steam contains the latent heat of vaporization in addition to sensible heat, so it carries more energy than liquid water at the same temperature; the boiling pot example explains that added heat at 100 °C goes into latent heat of vaporization rather than raising temperature [1]. Statement 2 is false: latent heat values for fusion (melting) and vaporization are distinct physical quantities and not equal; phase-change processes involve different energy amounts for melting vs vaporizing [2]. Statement 3 is correct: in a vapor-compression air-conditioner the evaporator absorbs heat from room air while the condenser rejects heat to the outside, so only statement 3 is correct.

Sources

1. [1] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 22: Vertical Distribution of Temperature > Latent Heat > p. 294
2. [2] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 22: Vertical Distribution of Temperature > Explanation > p. 295