Explain the following terms with one example each (a) Corrosion, (b) Rancidity.

(a) Corrosion: It is the process in which metals decay gradually by the action of air, moisture, or a chemical (such as an acid) on their surface.

Example: When iron is exposed to moist air for a long period of time, its surface acquires a coating of a brown, flaky substance called rust. Rust is mainly hydrated iron (III) oxide [Fe₂O₃.xH₂0].

(b) Rancidity: It is the aerial oxidation of fats and oils in foods followed by unpleasant smell and taste is called rancidity.

Rancidity spoils the food materials prepared in fats and oils which have been kept for a considerable time and makes them unfit for eating. Rancidity can be prevented by adding anti-oxidants to foods containing fats and oils.