Question

Why is ice at $273K$ more effective in cooling than water at the same temperature?

Answer 1

Hint: In ice water is converted from one state to another. So more energy is stored in ice than water at the same temperature. Latent heat is the key to this answer.

Complete step by step answer:
At $273K$ ice will absorb more heat from the substance to overcome latent heat of fusion but water will not absorb extra heat. Latent heat is that heat which is required to convert one state of a substance to another that is it is the energy which is required to convert solid to liquid or vapour state or liquid to vapour state at same temperature. Latent heat of fusion is heat required to convert the solid phase of a substance to liquid state at the same temperature and pressure. Similarly latent heat of vaporization is heat required to convert the liquid phase of a substance to vapour at the same temperature and pressure. As a result heat of substance will be absorbed by ice to overcome latent heat of fusion and cooling effect occurs. That is why ice causes more cooling than water at same temperature i.e. $273K$.
Additional information: Triple point is the temperature and pressure at which three different states of a substance i.e. solid, liquid and gas coexist. In other words they are in equilibrium with each other. Triple point of water is $273.1575K$ at $611.657$pascals.
Evaporation also causes cooling. Evaporation is a process in which liquid converts into vapour at room temperature. Main difference between evaporation and vaporization is that evaporation takes place at room temperature whereas vaporization takes place at boiling point. During evaporation water takes heat from the environment due to which cooling occurs. Due to this same reason water remains cold in clay pots, our body feels slightly cooler when we spray perfume on our body.

Note: Any substance causes cooling when it gains some heat from the environment. Due to this loss of heat from substance, the substance becomes cooler.