''$A$ perfect black body is black in colour.'' Is this statement true or false?

Two thermometers $A$ and $B$ are exposed to sunlight. The bulb of $A$ is painted black,but that of $B$ is not painted. Which of the following statements is correct regarding this case?

For a perfectly black body,the coefficient of emission (emissivity) is:

$A$ spherical body of emissivity $e = 0.6$ placed inside a perfect black body is maintained at temperature $T$. The energy radiated per second by the body will be:

$A$ 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?

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