Question

Which of the following represents a chemical change?

1) souring of milk
2) melting of chocolate
3) condensation of water
4) breaking of an egg shell

Answer 1

Souring of milk is a chemical change because it involves a transformation in chemical composition due to fermentation, unlike the other options which involve physical changes.

Step-by-step explanation:

The option that represents a chemical change is the souring of milk. During the souring process, bacteria convert lactose, the sugar in milk, into lactic acid through fermentation, leading to a change in the milk's chemical composition.

This is different from a physical change, where a substance changes form but not its chemical identity, like the melting of chocolate, condensation of water, or breaking an egg shell.

Answer 2

The answer is souring of milk, because it falls under the fermentation category, which is considered a chemical change