Question

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

7) Souring of milk

Answer 1

Part I - Definition

Physical change - A change in which no new substance is formed and only there is change in shape , size and state and color are termed as physical change.

Chemical change - A change in which new substances in form of products are formed due to occurrence of a chemical reaction is termed as chemical change.

Part II - Classification

Souring of milk is a chemical change because the milk loses its original form and undergoes a chemical reaction to change into sour -tasting lactic acid , which destroys the taste as well as composition of milk.

Final answer - Souring of milk is a chemical change