Q. Why do pipes carrying water often burst in cold countries during winter?
A. The temperature falls below 0°C in severe cold resulting in the conversion of water to ice. Since there occurs an increase in volume during this transformation, it exerts a great force which results in the bursting of water pipes.
Q. Why does water get cooled on evaporation?
A. Some heat energy is utilised during the process of evaporation. This energy is taken from the water itself thus producing a lowering of temperature in the remaining water. Hence, water gets cooled by evaporation.
Q. Explain why water gets cooled in an earthen pot much more than in a metal or glass container.
A. In an earthen pot, water gets evaporated through the pores of the pot quickly. As explained in the previous question, cooling is caused by evaporation. In the case of metal or glass container, there are no pores with the result that the rate of evaporation is quite low, thus there is only a slight fall in temperature.