Which of these is the subject of study in thermodynamics? a) energy changes b) only physical changes 3) only chemical changes 4) structure of atoms and molecules

a

Explanation:

The main subject of study in thermodynamics is the energy changes in a reaction or a system.

Generally speaking, thermodynamics is a branch of science that deals with the study of heat, work, temperature, and the energy of systems and how this energy is converted from one form to another. The subject of thermodynamics is governed by a series of laws known as the law of thermodynamics.

The correct option is a.