Question

The heat needed to turn 1 Kg of solid into liquid at its melting point is known as
A. Latent heat
B. Specific latent heat of vaporization
C. Specific latent heat of fusion
D. Specific latent heat of the substance

Answer 1

Hint: The temperature at which the solid reaches its melting point and turns into liquid is known as the melting point. It is a special temperature for every substance. The melting point of a solid is the same as the freezing point of the liquid, which is at this temperature, the states of solid and liquid are at equilibrium.
In this question, we will move by observing each of the given options.

Complete step by step answer:
Option A
Latent heat is the heat required to convert a solid into liquid or vapour, or liquid into vapour without a change in temperature. It is the energy absorbed or released by a substance during a change in its physical states without changing its temperature.
Option B
Specific latent heat of vaporization of a liquid is the amount of heat energy required to change 1 kg of the material in the liquid state at its boiling point to 1 kg of material in the gaseous state. For 1 kg of liquid 1 kg of vapour is released.
Option C
Specific latent heat of fusion of a solid is the amount of heat energy required to change 1 kg of the material in solid-state at its melting point to 1 kg of material in the liquid state. If you apply heat to ice, it will melt to water.
Option D
Specific latent heat of a substance is the same as latent heat, but in this case, heat is required for 1 kg of substance (for specific amount). The amount of energy required to change the state of 1 kg of a material is known as specific latent heat.
Hence the amount of heat needed to turn 1 Kg of solid into liquid at atmospheric pressure at its melting point is known as specific latent heat of fusion.

So, the correct answer is “Option C”.

Note:
Students should not get confused with the terms “Specific latent heat of vaporization” and “Specific latent heat of fusion”, these are two completely different terms as described in the solution.