Difficulty: Easy

Average Score: 84%

Which scenario demonstrates chemical weathering?

Rationale

Oxygen reacts with iron in rocks to form rust.

This scenario exemplifies chemical weathering, as it involves a chemical reaction that alters the composition of the rock material. The interaction of oxygen with iron leads to the formation of rust, which fundamentally changes the properties of the original rock.

A (Oxygen reacts with iron in rocks to form rust.) CORRECT

This choice accurately illustrates chemical weathering because it involves a chemical transformation where iron oxidizes in the presence of oxygen, resulting in rust. This reaction alters the mineral structure and integrity of the rock, demonstrating the process of weathering through chemical means.

B (Blown sand grinds down exposed rocks in a desert.) YOUR ANSWER

This option describes physical weathering, not chemical weathering. The mechanical action of sand particles eroding rocks through abrasion does not change the chemical composition of the rocks; it merely breaks them into smaller pieces.

C (Tree roots crack rocks as they grow into cracks.) YOUR ANSWER

This scenario exemplifies physical weathering as well. The physical force exerted by growing roots exerts pressure on the rocks, causing them to fracture. However, there is no chemical alteration of the minerals in the rocks involved in this process.

D (Cycles of hot and cold temperature form cracks in rocks.) YOUR ANSWER

This choice also depicts physical weathering. The expansion and contraction of rocks due to temperature changes lead to cracking but do not involve any chemical reactions that change the mineral composition of the rocks.

Conclusion

Chemical weathering involves processes that change the chemical composition of rocks, such as oxidation. The scenario of oxygen reacting with iron to form rust is a prime example of this process. In contrast, the other options describe physical weathering, which involves mechanical breakdown without altering the chemical makeup of the rocks. Understanding these distinctions is crucial for studying geological processes and landscape evolution.

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