Corrosion is the process of slowly eating up metals by gas and water vapours present in the atmosphere due to the formation of certain compounds like oxide, sulphides, carbonate, etc
. For example: Corrosion of copper and silver
Iron articles, when exposed to air and moisture for a prolonged time, acquire a brown flaky coating called rust.
Rusting reduces the structural strength of iron and can be prevented by painting, galvanising, greasing and alloying. For example- Galvanised iron, painted steel
Alloying is a method to prevent rusting by mixing a metal with one or more metals or non-metals. An alloy is a mixture of one or more metals or non-metals. Stainless steel is an example of an alloy made by mixing iron with some other metals and non-metals.
Chemical reactions
Corrosion of copper
![](https://df0b18phdhzpx.cloudfront.net/ckeditor_assets/pictures/1743908/original_Screenshot_2022-08-18_121619.png)
Rusting of iron
![](https://df0b18phdhzpx.cloudfront.net/ckeditor_assets/pictures/1743909/original_Screenshot_2022-08-18_121734.png)
Corrosion of silver4Ag + 2H2S + O2 → 2Ag2S + 2H2OSilver Hydrogen sulphide Silver sulphideTherefore option b is the correct answer