Question

why is ice at 273 K more effective in cooling than water at the temperature

Answer 1

because in Celsius it is 0 degree that's why

Answer 2

Ice is in solid state while water is in liquid state. Thus, ice will convert into liquid state by absorbing the latent heat of fusion. On the other hand, no such heat will  be absorbed by water as it is already in the liquid state. Hence, ice will absorb more energy than water at 273K. The more is the energy absorbed, the more is the cooling effect. As a result, the cooling effect of ice at 273 K is more than water at the same temperature. 

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