Explain the following terms with an example each:
(a) Corrosion    (b Rancidity.

(a) Corrosion: When a metal is attacked by the substances around it such as moisture, acid etc.,  It said to corrode and this process is called corrosion.

Corrosion causes damages to metal articles like car bodies, bridges, iron railings, ships and other substances of daily use.

(b) Rancidity: Fats and oils in food kept for long time get oxidised and become rancid and taste of food changes and causes infection on eating. This is called rancidity.

To prevent rancidity antioxidants (which prevent oxidation) are added to foods containing fats and oils. Rancidity can also be prevented by flushing out oxygen with an inert gas like nitrogen. For example, packets of food items like chips are flushed with nitrogen so that these can be used even after long duration.