Question 7

Chopping wood demonstrates a physical change.

Chopping wood is an action that alters the physical form of the wood without changing its chemical composition. This process involves breaking the wood into smaller pieces, which is characteristic of physical changes.

A) Milk becoming sour

This option represents a chemical change, as the souring of milk involves the alteration of its chemical structure due to bacterial activity. The transformation results in new substances being formed, indicating a chemical reaction.

B) Iron rusting

Rusting of iron is another example of a chemical change. It occurs when iron reacts with oxygen and moisture in the environment, forming iron oxide, which is a different substance from the original iron.

C) Chopping wood

Chopping wood is a clear example of a physical change. The wood's size and shape change, but its chemical properties remain the same, exemplifying the definition of a physical transformation.

D) Baking cookies

Baking cookies involves a series of chemical changes, where the ingredients undergo reactions due to heat to create new substances, such as the browning of sugars and the development of flavors and textures.

Conclusion

Chopping wood is definitively the correct answer as it solely involves a change in physical form without altering the wood's chemical structure. In contrast, the other options involve chemical changes, where new substances are generated, thereby distinguishing them from physical changes.