Question

The boiling hot water causes …………… severe burns than the steam at 100$^\circ$ C.
A. Less
B. More
C. Same
D. Can’t say

Answer 1

Hint:- The boiling hot water has only one type of heat that is specific heat and steam have two types of heat that is latent heat as well as specific heat. That means steam is carrying more heat energy with it, and when it gets contact with skin it burns more severely than water.

 Complete step-by-step solution:
Boiling hot water contains only a specific amount of heat energy, that is required to boil the water.
However, steam is formed from boiling water, as it contains the heat energy of boiling water and the latent heat of vaporization.
The steam has more heat energy, steam causes more severe burns than boiling water.
Hence, The boiling hot water causes less severe burns than the steam at 100$^\circ$ C.
Option (“A”) is the correct answer.

Additional Information:-
Latent heat ( L ) :- The quantity of heat absorbed or released when a substance changes its physical state at constant temperature ( e.g from solid to liquid at melting point or from liquid to gas at boiling point ).
Specific heat ( S ):- Specific heat is defined as the amount of heat needed to raise the temperature of one gram of a substance by 1 degree celsius.
Water has high specific heat capacity; it means water takes more amount of heat energy to raise its temperature compared to other substances. This is the reason why we use water as a coolant in a car's radiator.

Note:- Phase change is an isothermal process (a process is said to be an isothermal process if the temperature remains constant during the process). This latent heat or latent energy is the absorbed heat from its surroundings in order to overcome the attractive forces between its molecules as it changes from liquid to gas and in order to do work against the external atmosphere as it expands.