Head 2 Head: Corrosion
* (Corrosive) Water – Given enough time, iron either left in water, or in contact with water vapour in air, will rust – forming iron oxide.
* (Very corrosive) Battery acid – Due to the corrosive nature of sulphuric acid – commonly found in car batteries – the terminals on the battery tend to corrode after a few years.
* (Most corrosive) Hydrofluoric acid – Hydrofluoric acid is a relatively weak acid, yet it corrodes most metals and can even dissolve glass, so it’s commonly used in glass etching.