Which of the following is an example of corrosion?

All of the above

Corrosion occurs when a refined metal undergoes natural processes, converting it into a more stable oxide. Examples include the rusting of iron, the black coating on silver, and the green coating on copper.

Detailed Explanation:

1. What is Corrosion?
   • Corrosion is the gradual deterioration of materials (usually metals) through chemical or electrochemical reactions with their environment.
   • It typically occurs when metals react with oxygen, moisture, or other environmental factors, leading to the formation of oxides or other compounds.
2. Examples of Corrosion:
   • Rusting of Iron:
     • Iron reacts with oxygen and moisture in the air to form iron oxide (rust), weakening the metal.
   • Black Coating on Silver:
     • Silver reacts with sulfur compounds in the air, forming silver sulfide, which appears as a black tarnish.
   • Green Coating on Copper:
     • Copper reacts with carbon dioxide and moisture, forming copper carbonate (verdigris), which appears as a green layer.