☛ a. Zeroth law: If any two systems are in thermal equilibrium with the third system, then they are also in thermal equilibrium with each other.

☛ b. First law: First law of thermodynamic states that energy can neither be created nor be destroyed but it can only be converted from one form to another.

☛ c. Second law: This law states that “all processes in nature tend to occur with an increase in entropy and the direction of change always lead to the increase in entropy.”

☛ d. Third law: This law states that “The entropy of a perfect crystal of each element and a compound is zero at absolute zero.”