> it asked if there were any energy losses in the experiment.

No, when you burn something, no energy is lost. There is a fixed amount of energy in the universe and we cannot create or destroy energy. All we can do is transform it from one form to another.

When people say energy is "lost", it is the imperfect transformation of energy from one for to the other. If you turn mechanical energy into electrical energy (via an alternator or something) it's not a 100% conversion. You will turn 90% of the mechanical energy into electrical energy, and 10% of the energy into heat energy. The amount of energy is constant and unchanged, but the transformation from one form to the other is less than 100% efficient

When you burn something, no energy is lost. You are just converting matter (which is just bound up energy) into light energy, heat energy, and a different kind of matter (smoke and ash). The same amount of energy exists in the universe before you burned the thing and after