Explain why:
$(a)$ a body with large reflectivity is a poor emitter.
$(b)$ a brass tumbler feels much colder than a wooden tray on a chilly day.
$(c)$ an optical pyrometer (for measuring high temperatures) calibrated for an ideal black body radiation gives too low a value for the temperature of a red hot iron piece in the open,but gives a correct value for the temperature when the same piece is in the furnace.
$(d)$ the earth without its atmosphere would be inhospitably cold.
$(e)$ heating systems based on circulation of steam are more efficient in warming a building than those based on circulation of hot water.

(N/A) According to Kirchhoff's law of radiation,good absorbers of radiation are also good emitters. Since a body with high reflectivity reflects most of the incident radiation,it is a poor absorber. Therefore,it is also a poor emitter.
$(b)$ Brass is a good conductor of heat,while wood is a poor conductor. When you touch a brass tumbler,heat flows rapidly from your hand to the metal,causing a sensation of cold. With a wooden tray,heat transfer is very slow,so your hand loses less heat,making it feel warmer.
$(c)$ An optical pyrometer measures temperature based on the intensity of radiation. $A$ red-hot iron piece in the open has an emissivity less than $1$. Since it is not a perfect black body,it emits less radiation than a black body at the same temperature,leading to a lower temperature reading. In a furnace,the environment acts like a cavity (black body),so the iron piece effectively behaves as a black body,yielding an accurate reading.
$(d)$ The atmosphere acts as a blanket for the Earth,trapping infrared radiation emitted by the surface through the greenhouse effect. Without the atmosphere,this heat would escape into space,making the Earth's surface temperature drop drastically.
$(e)$ Steam at $100 \, ^{\circ}C$ contains significantly more energy than water at $100 \, ^{\circ}C$ due to the latent heat of vaporization $(540 \, cal/g)$. As steam condenses in the radiators,it releases this large amount of latent heat,making it more efficient for heating.