Which statement best describes how sacrificial anodes protect metal surfaces from corrosion?

• A. A coating prevents corrosion.
• B. A more reactive metal is attached to the protected metal; the sacrificial metal oxidizes preferentially, protecting the steel.
• C. An electrical potential is applied to stop oxidation.
• D. Protected metal is more reactive; sacrificial metal remains inert.

Answer: (B)

Sacrificial anodes protect by using a more active metal to create a galvanic couple in an electrolyte. The attached, more reactive metal has a more negative electrochemical potential, so when it’s connected to the metal we want to protect, it becomes the anode and oxidizes preferentially. That means the sacrificial metal corrodes, while the protected metal is kept at a lower, less corrosion-friendly potential and stays protected. This process happens without any external power source or barrier coating; it relies on the natural electrochemical difference between the metals. The protected metal isn’t the more reactive one, and the sacrificial element isn’t inert, which is why this arrangement works.