Question

what is the definition of thermal equilibrium
state in which all parts of a system are at the same temperature
sum of the kinetic energies of all the particles that make up an object
transfer of thermal energy by direct contact of two objects or portions of matter
a measure of the average kinetic energy of an objects particles

Explanation:

Thermal equilibrium is a state where there is no net heat transfer between parts of a system. This occurs when all parts of the system reach the same temperature. The first option correctly describes this state. The second option refers to internal energy (sum of kinetic energies of particles). The third option is about heat transfer (conduction). The fourth option is the definition of temperature (average kinetic energy of particles).

Answer:

"state in which all parts of a system are at the same temperature"