Define Thermal equilibrium . State the zeroth law of thermodynamics (or) How does it lead to zeroth Law of Thermodynamics ?

Explanation

Thermal Equilibrium : Two systems are said to be in thermal equilibrium with each other if they are at same temperature .
Explanation : If two different temperature of system are kept in contact . Heat transfer from hot to cold body . If they are at same , then they are said to be in thermo equilibrium .
Generally at thermal equilibrium the temperature of two systems is same . This concept leads to Zeroth law of thermodynamics .
Zeroth law of thermodymanics : It states that if two systems say A & B are in thermal equilibrium with a third system 'C' separately then the two system A and B are also in thermal equilibrium with each other .