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 temperature and volume
3. It is independent of temperature and volume
4. It depends on the temperature but independent of volume

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This question was previously asked in

NDA (Held On: 22 April 2018) General Ability Test Previous Year paper

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Answer 1

CONCEPT

Latent Heat: The amount of heat required per mass to change the state of any substance. It is a hidden form of heat.

In the process of melting or vaporization, the temperature remains constant. The amount of heat needed to change the state of matter having mass m is-
Q = m L [Q= heat required, m = mass of the body, L = latent heat]

Latent heat of fusion: It is the heat required for 1 kg of substance to change it from solid to liquid state without change of temperature.

Latent heat of fusion of ice = 3.36 × 10⁵ J/kg
In CGS = 80 cal / gm.
Latent heat of Vaporization: It is the heat required for 1 kg of substance to change it from liquid to gaseous state without change of temperature.
Latent heat of vaporization of water = 2.25 × 10⁶ J/kg.
In CGS = 536 cal / gm

EXPLANATION

The latent heat is hidden heat for change in state.

In the process of change of state temperature remains constant.

⇒ Latent heat is fixed at a given temperature, thus independent of temperature

The volume of the object while changing the state is fixed.

⇒ Latent heat is independent of volume.

∴ Statement 1and 3 are true ⇒ Option 2 is correct.