Which of the choices is not a statement or direct application of the second law of thermodynamics? There are no 100% efficient heat engines. The change in internal energy of a system can be found by combining the heat energy added to a system minus the work done by the system. Heat energy naturally transfers from a high temperature substance to a low temperature substance. All natural processes tend toward states of increased entropy.

The change in internal energy of a system can be found by combining the heat energy added to a system minus the work done by the system is not a direct application of second law of thermodynamics.

Explanation:

Second law of thermodynamics states that heat can be transfer spontaneously from high temperature to low temperature only.

The change in internal energy of a system can be found by combining the heat energy added to a system minus the work done by the system is not a direct application of second law of thermodynamics because according to the second law of thermodynamics it is impossible in any system for heat transfer from a source to completely convert to work done in a cyclical process( bring the system to its original stage after each cycle) in which the system then return to it's original stage.