$A$ black metal foil is kept at a distance $d$ from a circular heater. The power absorbed by the foil is $P$. If the temperature of the heater and the distance are both doubled,the power absorbed by the foil will be ..... $P$.

The temperature of a piece of iron is $27^{\circ}C$ and it is radiating energy at the rate of $Q \text{ kW m}^{-2}$. If its temperature is raised to $151^{\circ}C$,the rate of radiation of energy will become approximately ....... $Q \text{ kW m}^{-2}$.

The ratio of the energy of emitted radiation of a black body at $27^{\circ}C$ and $927^{\circ}C$ is:

The spectral energy distribution of a star is maximum at a temperature twice that of the Sun. The total energy radiated by the star is

If the ambient temperature is $300 \ K$,the rate of cooling at $600 \ K$ is $H$. In the same surroundings,the rate of cooling at $900 \ K$ is:

$Assertion :$ Bodies radiate heat at all temperatures.
$Reason :$ Rate of radiation of heat is proportional to the fourth power of absolute temperature.