Question

If a substance reacts with oxygen, the chemical reaction is most likely a what?

Answer 1

This is an redox reaction, a combustion reaction.
For example:

4Al + 3O₂ = 2Al₂O₃
Al - 3e⁻ = Al⁺³
O₂ + 4e⁻ = 2O⁻²

Answer 2

the answer would be a combustion reaction