The absorption coefficient of an open window is:

Two identical objects $A$ and $B$ are at temperatures $T_A$ and $T_B$ respectively. Both objects are placed in a room with perfectly absorbing walls maintained at temperature $T$ $(T_A > T > T_B)$. The objects $A$ and $B$ attain temperature $T$ eventually. Which one of the following is the correct statement?

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

Which of the following laws states that "good absorbers of heat are good emitters"?

$A$ piece of blue glass heated to a high temperature and a piece of red glass at room temperature are taken inside a dimly lit room. Then:

What would happen if the greenhouse effect were not present?