what is thermal energy?\no the average overall volume of a system\no the total number of molecules in a…

Brief Explanations:

Thermal energy is related to the motion of particles. The kinetic energy of moving particles in a system represents thermal energy. Volume and number of molecules are not definitions of thermal energy. Temperature is a measure related to average kinetic - energy but not the same as thermal energy itself.

Answer:

the kinetic energy of particles in a system