In cathodic protection, which statement correctly describes how it works?

In cathodic protection, which statement correctly describes how it works?

• A. It only works without water present.
• B. More active metals oxidize and corrode to protect less reactive cathodes.
• C. The protected metal becomes the anode.
• D. It uses thermal diffusion for protection.

Answer: (B)

Cathodic protection works by using a more reactive metal as a sacrificial anode. This active metal oxidizes and corrodes in preference to the metal structure it protects. The electrons it loses flow to the protected metal, making that surface the cathode and keeping it from oxidizing. In practice, the sacrificial metal corrodes while the protected metal remains safe, which is why the description says a more active metal oxidizes and corrodes to shield the less reactive cathode. This process requires an electrolyte (often water-containing environments), so it isn’t about water being absent; it’s about the electrochemical setup. The protected metal becomes the cathode, not the anode, and there’s no role for thermal diffusion in this protection.

Cathodic protection works by using a more reactive metal as a sacrificial anode. This active metal oxidizes and corrodes in preference to the metal structure it protects. The electrons it loses flow to the protected metal, making that surface the cathode and keeping it from oxidizing. In practice, the sacrificial metal corrodes while the protected metal remains safe, which is why the description says a more active metal oxidizes and corrodes to shield the less reactive cathode. This process requires an electrolyte (often water-containing environments), so it isn’t about water being absent; it’s about the electrochemical setup. The protected metal becomes the cathode, not the anode, and there’s no role for thermal diffusion in this protection.