How could you verify that soda drinks are acidic using corrode metals

Metals tarnish when they are oxidized, or lose electrons, generally due to the presence of and reaction with sulfur compounds or oxygen, depending on the metal, creating a coating of metal oxide or metal sulfide, which can look like rust, tarnish, or patina, to name a few common types of oxidation product. When tarnished metal is exposed to an acid, the metal's oxidation is reversed, removing the corrosion layer and thereby cleaning the metal. The level of acidity can be modest. Soda is ten times less acidic than lemon juice and far less acidic than your own stomach.

While unproven, it uses facts to support part of a conclusion. it is still factual and has predictive power, however.