Q.7:- Why is ice at 273 K more effective in cooling than water at the same temperature ?
Cooling takes place when heat is removed from a system. In case of ice at 273 K, it will take latent heat from the medium to convert itself into water at 273 K and then into water at a higher temperature. Thus, in case of ice at 273 K there will be a change in physical state, whereas in case of water at 273 K there will be no change in state. Hence lesser energy will be taken from the medium.