Question

1) why does water become cold if we add some ice cubes to it?

2) latent heat of evaporation of two liquids A B is 100 J/kg and 150 J/kg respectively. Which one can produce more cooling effect and why?

Answer 1

1) Water becomes cold if we add some ice cubes to it because of conservation of energy.
Heat is a form of energy. The temperature of water is more than ice cubes, so the heat flows from the water to ice cubes. The heat gained by the melting of ice cubes is equal to the heat lost by liquid water. As the water loses heat, its temperature falls.

2) Liquid B will produce more cooling effect because it has high latent heat of evaporation so it will take more heat from the surface and will produce more cooling than liquid A.