Good absorbers of heat are

When $170 \text{ J}$ of energy is incident on a surface of a body, $17 \text{ J}$ of energy is reflected by it. If the coefficient of absorption is $0.7$, then the amount of energy transmitted will be (in $\text{ J}$)

Why are the bottom layers of cooking vessels kept black in color?

If $e_\lambda$ and $a_\lambda$ are the emissive power and absorptive power of a body respectively,and $E_\lambda$ is the emissive power of a perfectly black body,what is the relation according to Kirchhoff's law?

Which of the following is best close to an ideal black body?

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