Will 1 liter's worth of electrolyzed water (2H2 and O2 gas) when combusted produce 1 liter's worth of water?

Question

Let's say you have a container filled with exactly 1L of pure H2O. That water is then completely electrolyzed to produce 2 parts H2 gas and 1 part O2 gas. If then those gases, still in the same 1L container, are combusted, will the result of combustion, besides heat, produce that original 1L of water?

Answer 1

Not only will the result be exactly 1L of water, the energy produced by the combustion will equal the energy needed to electrolyze it.
That is, theoretically. In reality, it would require some energy to put 3 moles of gas (at a temperature where liquid water exists) into a one liter flask.