If there were no atmosphere on Earth,its temperature would be ...... .

$A$ body has a black spot on it. When the body is heated and taken into a dark room,the black spot glows more brightly. This can be explained by which of the following?

If a black body at $400 \ K$ surrounded by atmosphere at $300 \ K$ has a rate of cooling '$R_0$',the same body at $900 \ K$,surrounded by the same atmosphere,will have a rate of cooling nearly:

Heat energy is incident on the surface of a material at the rate of $1000 \ J \ min^{-1}$. If the coefficient of absorption is $0.8$ and the coefficient of reflection is $0.1$,then the amount of heat energy transmitted through the material in $5$ minutes is: (in $J$)

If $E$ is the total energy emitted by a body at temperature $T \ K$ and $E_{max}$ is the maximum energy emitted by it at the same temperature,then:

$A$ body,which emits radiations of all possible wavelengths,is known as ...........