I believe it becomes less dense, bc when you heat something it’s molecules spread further apart.
It would be endothermic because the log is in the system.
3 elements are present in HCOOH - hydrogen, oxygen, and carbon.
Answer: The bubbles produced are most likely due to oxygen.
Explanation:
Photosynthesis is a phenomenon in which green plants containing chlorophyll use sunlight as a source of energy to convert carbon dioxide and water to form glucose and oxygen.
The balanced chemical reaction for photosynthesis is:

Thus the bubbles produced are most likely due to oxygen.