$A$ perfect black body is ........

$A$ sphere,a cube,and a thin circular plate,all made of the same material and having the same mass,are initially heated to a temperature of $1000^{\circ}C$. Which one of these will cool first?

$A$ 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:

$Assertion :$ $A$ body that is a good radiator is also a good absorber of radiation at a given wavelength.
$Reason :$ According to Kirchhoff's law,the absorptivity of a body is equal to its emissivity at a given wavelength.

There is a rough black spot on a polished metallic plate. It is heated up to $1400 K$ approximately and then at once taken into a dark room. Which of the following statements is true?

In the rainy season,on a clear night,the black seat of a bicycle becomes wet because: