Part (a) on hot sunny day, we sprinkle water on roof or open ground because the water can absorb the heat and get converted into vapours.Since water absorb heat so temperature of surrounding fell down and we get cooling.Part (b) As perspiration takes place it will gives sweat, sweat will absorb the heat from our body it makes your skin feel cooler when its wet.Hence in evaporation of sweat will cause absorption of heat making your body cold.Part (c) Ice has latent heat, it will absorb the heat from burnt skin. Ice get converted into liquid. So it will absorb heat and gives relaxation from burning.