why ice at 0 degree celcius gives more cooling effect than water at 0 degree celcius?
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 or 0o C. The more is the energy absorbed, the more is the cooling effect. As a result, the cooling effect of ice at 273 K or 0o C is more than water at the same temperature.