Answer: Option (3) is the correct answer.
Explanation:
When chemical energy is converted into thermal energy then energy between the chemical bonds releases. Due to this energy release, the surrounding molecules move faster.
As a result, there will be increase in the thermal energy of molecules of the substance.
For example, chemical energy releases when coal is burned and water over it changes into steam.
Thus, we can conclude that only the amount of thermal energy changes when chemical energy is converted into  thermal energy.
