Which of the following statements is wrong?

The sun radiates electromagnetic energy at the rate of $3.9 \times 10^{26} \ W$. Its radius is $6.96 \times 10^8 \ m$. The intensity of sunlight at the solar surface will be (in $W/m^2$):

An ideal black body at room temperature is thrown into a furnace. It is observed that:

$A$ hot and a cold body are kept in a vacuum,separated from each other. Which of the following causes a decrease in the temperature of the hot body?

$A$ solid cylinder of length $L$ and radius $r$ is heated up to the same temperature as that of a cube of edge length $a$. If both have the same material,volume,and are allowed to cool under similar conditions,then the ratio of the amount of radiation emitted will be (Neglect radiation emitted from the flat surfaces of the cylinder).

$A$ thermopile is used for: