Which type of metal is more prone to rust when exposed to moisture?

• A. Alloys.
• B. Non-ferrous metals.
• C. Plastics.
• D. Ferrous metals.

Answer: (D)

Rust is iron oxide that forms when iron reacts with oxygen in the presence of water. Only metals that contain iron—ferrous metals—are prone to this specific form of corrosion, so they rust more readily when moisture is present. Non-ferrous metals like aluminum or copper do not form rust in the same way; they corrosion via other oxide layers or protective films. Plastics aren’t metals and won’t rust at all. While some ferrous alloys (like stainless steel) resist rust due to protective layers, without such protection ferrous metals typically rust when exposed to moisture.