Question

(B) Classify the following as physical or chemical change.

13) Baking bread

Answer 1

Part I - Definition

Physical change - A change in which no new substance is formed and only there is a change in shape, size, state, and the color is termed as physical change. It can be reversed

Chemical change - A change in which new substances in form of products are formed due to the occurrence of a chemical reaction is termed a chemical change. It cannot be reversed

Part II - Classification

• Baking a bread is a chemical change.
• Because the carbon dioxide which is present in the dough of bread expands with temperature rise
• The fermentation reaction of yeast evaporates and their vapor expands the dough with rising temperature.
• Thus yeast produces a completely new product that cannot be reversed back to its original form.

Final answer - Baking a bread is a chemical change