a student claimed that the bubbles in boiling water were oxygen. are they correct? explain your answer

Answer 1

h ttps://www.thoughtco.com/what-are-the-bubbles-in-boiling-water-4109061

Note in reading the info in the above url that before the water boils there is an out gassing of the small amount of air dissolved in the water. Air is a mixture of oxygen, nitrogen, and a few other gases so in that respect some of the bubbles do contain oxygen but that doesn't come from the decomposition of H2O into H2 and O2. When water comes to a rolling boil the bubbles are water vapor.