Explain why:

(a) we wear woollen clothes in winter?

(b) the water pipes are covered with cotton during very cold weather?

(a) Woollen clothes have fine pores which are filled with air and both wool and air are insulators of heat. They do not allow the heat to escape through them and keep us warm. So we wear woollen clothes in winter.

(b) Cotton has air trapped in its fine pores. Both cotton and air are insulators of heat which do not pass heat from the water inside the pipes to the outside atmosphere and prevents the water from freezing. So the water pipes are covered with cotton during very cold weather