In which process is the rate of transfer of heat maximum?

Which of the following is the correct device for the detection of thermal radiation?

$Assertion :$ $A$ hollow metallic closed container maintained at a uniform temperature can act as a source of black body radiation.
$Reason :$ All metals act as black bodies.

Shown below are the black body radiation curves at temperatures $T_1$ and $T_2$ $(T_2 > T_1)$. Which of the following plots is correct?

The intensity of direct sunlight on a surface normal to the rays is $I_0$. What is the intensity of direct sunlight on a surface,whose normal makes an angle of $60^{\circ}$ with the rays of the sun?

The absorption coefficient value of a perfect black body is