State the second law of thermodynamics and explain it.

Explanation

II law of thermodynamics :
Statements :
i). .It is impossible for a self acting machine unaided by any extemal agency to convert heat from a body at low temperature to a body at higher temperature".
ii) "All spontaneous processes are thermodynamically ineversible and entropy of the system increases in all spontaneous processes.
iii) "For any spontaneous process taking place in an isolated system, the change in entropy `(triangleS)` is positive."