Which of the following statements about latent heat for a given substa

Which of the following statements about latent heat for a given substance is/are correct ?

  • 1. It is fixed at a given temperature.
  • 2. It depends upon the temperature and volume.
  • 3. It is independent of temperature and volume.
  • 4. It depends on the temperature but independent of volume.

Select the correct answer using the code given below :

2
1 and 3
4 only
1 and 4
This question was previously asked in
UPSC NDA-1 – 2018
Statement 1 is correct: For a specific substance at a given pressure, the latent heat associated with a phase transition (like melting or boiling) is fixed at the transition temperature. Statement 4 is also considered correct in the context that the value of latent heat is characteristic of the specific transition temperature, though the phrasing “depends on the temperature” can be ambiguous.
– Latent heat is the energy absorbed or released during a phase change at constant temperature and pressure.
– Statement 1 accurately reflects that for a specific phase transition at standard conditions, the latent heat value is constant at the transition temperature.
– While the phase change occurs *at* a constant temperature, the *value* of the latent heat can technically vary with the pressure, which in turn affects the transition temperature. Statement 4 might be interpreting “depends on the temperature” as being specific to the transition temperature value, and “independent of volume” in the sense that the volume of the substance isn’t a variable determining the latent heat value itself, unlike say, specific heat capacity which can be defined at constant volume.
Statement 2 is incorrect as volume is not a primary variable defining latent heat. Statement 3 is incorrect as latent heat is fundamentally linked to the transition temperature. Given the options, 1 and 4 are the most plausible correct statements, despite the awkward phrasing of 4. This suggests that the question setter considered both 1 and 4 as correct representations, with 4 perhaps indicating dependence on the *specific transition temperature*.