Question

which concept is defined by zeroth of thermodynamics

Answer 1

that energy can neither be created nor destroyed

Answer 2

$\fbox{ \fbox{ \tt \: Zeroth \: Law \: of \: Thermodynamics \: }}$

The zeroth law of thermodynamics states that if two thermodynamics system are each in a thermal equilibrium with a third one,then they are in thermal equilibrium with each accordingly thermal equilibrium between systems is a transitive relation.