(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.

Example:

4Fe (s) + 3O2 (g) + 6H2O (l) → 4Fe(OH)3 (s)

This is the formation of rust, which is hydrated iron oxide.

(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.

Example:

The taste and smell of butter change when kept for a long time.

Rancidity can be avoided by:

• Storing food in airtight containers
• Storing food in refrigerators
• Adding antioxidants
• Storing food in an environment of nitrogen