The galvanic series has been constructed from measurements __________.

• A. Seawater
• B. Freshwater
• C. Air
• D. Vacuum

Answer: (C)

The galvanic series is built by comparing the electrochemical potentials of different metals in a common electrolyte. In practice, it’s seawater that sets the reference because it provides a conductive ionic environment where galvanic differences between metals are actually realized when they’re in contact. Measuring open-circuit potentials and galvanic responses in seawater yields a ranking that reflects how metals will behave in marine or saltwater conditions. Freshwater would produce a different ordering due to lower ionic strength, and in air or vacuum there isn’t a suitable electrolyte for meaningful galvanic coupling, so those environments don’t establish the same practical series.