Which description accurately explains galvanic corrosion when two metals are in contact in an electrolyte?

• A. The more noble metal corrodes faster.
• B. Neither metal corrodes due to protective oxide.
• C. The less noble metal (anode) corrodes preferentially.
• D. Corrosion is independent of material nobility.

Answer: (C)

When two dissimilar metals are in contact in an electrolyte, they form a galvanic pair where the metal with the lower nobility becomes the anode. At the anode, oxidation occurs—the metal loses electrons and corrodes—while the more noble metal acts as the cathode and is protected from corrosion. The electrolyte allows ion movement and completes the electrical circuit, letting electrons flow from the anode to the cathode and driving the corrosion at the anodic metal. Because of this, the less noble metal corrodes preferentially in the couple. The rate depends on the potential difference between the metals and their relative surface areas, but the core idea is that corrosion concentrates on the anodic, less noble metal.