Explain why:
a body with large reflectivity is a poor emitter
The provided context does not contain the necessary information to explain why a body with large reflectivity is a poor emitter.
a brass tumbler feels much colder than a wooden tray on a chilly day
This happens because of conduction, which is the mechanism of transfer of heat between two adjacent parts of a body because of their temperature difference.
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
The provided context mentions radiation but lacks the specific details about black body radiation and pyrometers required to explain this.
the earth without its atmosphere would be inhospitably cold
The provided context does not contain information regarding the earth's atmosphere or its temperature regulation.
heating systems based on circulation of steam are more efficient in warming a building than those based on circulation of hot water
The provided context does not contain information regarding heating systems or the properties of steam and hot water.
Explanation
The provided context is insufficient to fully answer the question. It contains the question text itself, a definition of conduction, and a header for radiation, but it fails to retrieve the key explanatory paragraphs from the NCERT textbook. Specifically, it lacks the concepts of Kirchhoff's law (for part a), comparative thermal conductivity (for part b), black body radiation and emissivity (for part c), the greenhouse effect (for part d), and latent heat (for part e). Therefore, a comprehensive exam-ready answer cannot be generated using only the provided facts.