What term describes the surface layer that develops on copper oxide?

• A. Patina
• B. Verdigris
• C. Tarnish
• D. Oxide

Answer: (A)

Patina is the film that forms on copper as it ages and oxidizes. It’s a general term for the surface layer that develops, often taking on a greenish hue in copper due to various copper compounds. Verdigris is a specific green patina (a type of patina formed from copper salts), while tarnish refers to dulling or discoloration on metals in general, and oxide describes the actual chemical oxide layer. Because the question asks for the broad surface layer that appears on copper as it oxidizes, patina is the best-fitting term.