What holds combinations of atoms together in molecules?

If you want to create an electrical current, which situation would produce a solution capable of this

Asuspension of yeast cells is being grown under anaerobic conditions such that glucose is degraded to ethanol and carbon dioxide. if one wishes to follow this process by monitoring the release of 14co2, at which positions in the glucose molecule would the 14c label need to be incorporated?

What type of energy conversion occurs when you place your feet near the fire place and they become warm