Cooking an egg is an example of which type of change?

• A. Physical change
• B. Phase change
• C. Chemical change
• D. Nuclear change

Answer: (C)

Cooking an egg mainly shows how heating can cause chemical changes in biomolecules. The heat denatures the proteins in the egg white and yolk, then they coagulate to form a solid network. This creates new properties—texture, color, and firmness—that aren’t simply due to a rearrangement of the same molecules; the protein structure is altered in a way that isn’t easily reversed just by cooling. It isn’t a phase change like melting or freezing, and there are no changes to the nucleus involved, so the situation aligns with a chemical change.