Explain the following terms with one example each.

solution:
(a) Corrosion- Corrosion is defined as a process where materials, usually metals, deteriorate as a result of a chemical reaction with air, moisture, chemicals, etc.

For example, iron, in the presence of moisture, reacts with oxygen to form hydrated iron oxide.

$4 \mathrm{Fe}+3 \mathrm{O}_{2}+\mathrm{nH}_{2} \mathrm{O} \rightarrow 2 \mathrm{Fe}_{2} \mathrm{O}_{3} \cdot \mathrm{nH}_{2} \mathrm{O}$

Hydrated iron oxide

This hydrated iron oxide is rust.

(b) Rancidity - The process of oxidation of fats and oils that can be easily noticed by the change in taste and smell is known as rancidity

For example, the taste and smell of butter changes when kept for long.

Rancidity can be avoided by-

(1) Storing food in air tight containers.

(2) Storing food in refrigerators.

(3) Adding antioxidants.

(4) Storing food in an environment of nitrogen.