Which action demonstrates a physical change?

Rationale

Chopping wood demonstrates a physical change.

Chopping wood alters the physical form of the wood without changing its chemical composition. This process results in smaller pieces of wood, but the wood itself remains chemically the same as it was before being chopped.

A (Milk becoming sour) YOUR ANSWER

This process involves a chemical change where the lactose in milk is converted into lactic acid by bacteria, resulting in a sour taste. The transformation alters the chemical structure of the substances involved, making it a clear example of a chemical reaction rather than a physical change.

B (Iron rusting) YOUR ANSWER

Rusting is a chemical change that occurs when iron reacts with oxygen and moisture, forming iron oxide. This reaction alters the chemical composition of the iron, leading to the formation of a new substance (rust), which is indicative of a chemical change rather than a physical alteration.

C (Chopping wood) CORRECT

Chopping wood is a physical change because it only affects the size and shape of the wood pieces without altering their chemical structure. The composition of the wood remains the same, demonstrating a simple physical alteration rather than a chemical transformation.

D (Baking cookies) YOUR ANSWER

Baking cookies involves a series of chemical changes, including the Maillard reaction and caramelization, which alter the ingredients' chemical structures. This process creates new substances with different flavors and textures, making it a prime example of a chemical change.

Conclusion

Physical changes involve alterations in form or appearance without changing the substance's chemical identity. Among the options presented, chopping wood is the only action that exemplifies a physical change, as it retains the original chemical composition of the wood. In contrast, the other choices represent chemical changes, where new substances are formed through chemical reactions.

Which action demonstrates a physical change?

Chopping wood demonstrates a physical change.

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