Which type of insulator (Black paper or white wadding) will slow down the rate of cooling? Why?
We know, black surface is a good conductor of heat while white surface is a poor conductor of heat. Hence, when the container is covered with black paper, the good conducting black paper conducts heat from the inside of the container to the outer environment, as temperature of boiled water is greater than temperature of outer air and heat flows from a region of higher temperature to a region of lower temperature. On the other hand, white paper being a bad conductor of heat cannot conduct heat quickly to the outer air and hence the heat is preserved within the water.
