Answer: The physical properties of iron oxide are that it is an odorless, red-brown solid, and that it is insoluble. Depending on the chemical formula, one of the chemical properties is its combustibility. If the chemical formula is Fe2O3, it is not combustible. If the formula is FeO, it is readily combustible.
The correct answer is C, too deep in the Earth to collect. Hope this helps!
The answer to this is surface wave i think
