Heat and Mass Transfer
Kirchhoff's law states that

The total radiation from a black body per second per unit area is directly proportional to the fourth power of the absolute temperature
None of these
The ratio of the emissive power and absorptive power of all bodies is the same and is equal to the emissive power of a perfectly black body
The wave length corresponding to the maximum energy is proportional to the absolute temperature

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Heat and Mass Transfer
According to Prevost theory of heat exchange

Heat transfer in most of the cases takes place by combination of conduction, convection and radiation
It is impossible to transfer heat from low temperature source to t high temperature source
All bodies above absolute zero emit radiation
Heat transfer by radiation requires no medium

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