Identical mild steel samples are placed in 6 different corrosion cells.

Rank these corrosion environments from most to least corrosive and explain your reasoning:

(1) Deionized water

(2) Aerated sodium chloride solution (NaCl 35 g/l)

(3) Sodium chloride solution (NaCl 35 g/l)

(4) pH 4 buffered solution. The solution includes 35 g/l of NaCl

(5) pH 9 buffered solution. The solution includes 35 g/l of NaCl

(6) Sodium chloride (NaCl 35 g/l) with carbon steel and copper galvanic couple.