According to Kelvin-Planck’s statement of the second law of thermodynamics, which of the following statements is correct?
Kelvin-Planck statement: It is impossible for a system to accept a given amount of heat from a high-temperature medium and to deliver an equal amount of work output, meaning that a heat engine cannot have a thermal efficiency of 100% or unity. On the other hand, a system converting work into an equivalent heat is possible.
Clausius statement: It is impossible for heat to move by itself from a low-temperature medium to a high-temperature medium. This means that heat transfer can only happen spontaneously in the direction of temperature drop.