Which of the following is a form of corrosion that proceeds uniformly over the surface?

• A. General corrosion
• B. Pitting
• C. Filiform
• D. Crevice

Answer: (A)

Uniform attack across the entire exposed surface, known as general or uniform corrosion, is the form described. This happens when electrochemical conditions are essentially the same everywhere on the metal, so oxidation and reduction proceed at similar rates across the whole area. The metal thins evenly and the surface may take on a uniform oxide layer. This contrasts with localized forms such as pits, which are deep, small holes caused by breakdown of protective films at specific spots; crevice corrosion, which occurs in confined gaps where electrolyte flow is restricted; and filiform corrosion, which runs under coatings in thread-like tracks. When a question specifies that corrosion proceeds uniformly over the surface, general corrosion is the best fit. It’s typically indicated by uniform weight loss and even thinning rather than isolated defects.