Which term describes the gradual wearing away of a metal due to reactions with oxygen, often accelerated by water (for example rust)?

• A. Corrosion
• B. Corrosive
• C. Ionic charge
• D. Periods

Answer: (A)

This is about corrosion. Corrosion is the gradual wearing away of a metal as it reacts with oxygen in the air, and water often speeds this up by acting as an electrolyte that enhances the electrochemical reactions. Rust is the familiar example of corrosion on iron, forming hydrated iron oxide when iron meets oxygen and moisture. The other terms don’t describe a process: corrosive is an adjective for something that can cause corrosion, while ionic charge and periods relate to chemistry concepts that aren’t about the metal’s deterioration.