relating to the oxygen theory of combustion, describe what concepts in the theory are still unanswered (if any).

The Oxygen Theory of Combustion, proposed by Antoine Lavoisier in the 18th century, revolutionized the understanding of combustion, respiration, and rusting. According to this theory, combustion is a reaction with oxygen, specifically a process of oxidation. This replaced the previous phlogiston theory, which suggested that a fire-like element called phlogiston was released during combustion.

As for unanswered questions, it's important to note that the Oxygen Theory of Combustion is a well-established and widely accepted theory. It has been refined and expanded upon with the development of more advanced theories and models, particularly in the field of physical chemistry.

However, there are complex combustion processes, such as those involving certain types of fuels or occurring under extreme conditions, that may not be fully explained by the basic Oxygen Theory of Combustion alone. These situations often require a more detailed understanding of chemical kinetics, fluid dynamics, heat transfer, and other factors.

In addition, while the Oxygen Theory of Combustion provides a general explanation for combustion processes, it does not provide a detailed description of all the intermediate steps and species involved in complex combustion reactions. This is an area of ongoing research in combustion science.

So, while the basic concepts of the Oxygen Theory of Combustion are well-established, there are still many details and complexities of real-world combustion processes that are the subject of ongoing research.