State the various statements of second law of thermodynamics.

Explanation

(i)Entropy statement: Whenever a spontaneous process takes place, it is accompanied by an increase in the total entropy of the universe"
(ii)Kelvin-Planck statement: It is impossible to take heat from a hotter reservoir and convert it completely into work by a cyclic process without transferring a part of heat to a cooler reservoir
(iii)Efficiency statement: Even an ideal, frictionless engine cannot convert 100% of its input heat into work.
Efficiency =`(T_1-T_2)/T_1`
% Efficiency =`[(T_1-T_2)/T_1]xx100`
% Efficiency =`["Output"/"Input"]xx100`
% Efficiency < 100%
(iv)Clausius statement: Heat flows spontaneously from hot objects to cold objects and to get it flow in the opposite direction, we have to spend some work.