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

Question 20. Explain the following terms with one example each.
(a) Corrosion
(b) Rancidity
Answer:
Corrosion: It is the process in which metals are slowly eaten up by the action of air moisture or chemicals. For example rusting is a form of corrosion in which iron is eaten up by the action of air and moisture and a reddish brown coating of iron oxide is formed as shown in the following chemical reaction.

Rancidity: When the substance containing oils and fats are exposed to air they get oxidised and become rancid due to which their smell, taste and colour change. This process is known as rancidity. For example when a when butter is kept open for a long time then its smell and taste gets changed.