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Which of the following is an example of physical weathering?

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Rationale

The cracking of a rock caused by the freezing and thawing of water.

This phenomenon, known as frost wedging, is a classic example of physical weathering, which breaks down rocks into smaller pieces without altering their chemical composition. The repeated expansion and contraction of water as it freezes and thaws exert mechanical stress on the rock, leading to its fragmentation.

A (The cracking of a rock caused by the freezing and thawing of water.) CORRECT

This choice accurately describes physical weathering, where mechanical processes break rocks apart. The freeze-thaw cycle creates cracks in the rock as water seeps in, freezes, and expands, eventually causing the rock to fracture without changing its chemical structure.

B (Sediments being transported in a stream.) YOUR ANSWER

While this process involves the movement of materials, it does not qualify as physical weathering. Instead, it reflects erosion and transport, which are distinct processes involving the relocation of weathered materials rather than the direct breakdown of rocks.

C (A sandbar forming in a stream.) YOUR ANSWER

The formation of a sandbar is a result of sediment deposition rather than weathering. This process occurs when sediments carried by the water settle in a specific area, leading to the accumulation of material but not involving the physical alteration of the source rocks.

D (Acid rain dissolving a statue.) YOUR ANSWER

This choice describes chemical weathering, where chemical reactions, such as those between acidic precipitation and minerals, lead to the breakdown of materials. Unlike physical weathering, which involves mechanical processes, this option involves a change in the chemical composition of the statue.

Conclusion

Physical weathering involves the mechanical breakdown of rocks without altering their chemical makeup, exemplified by the freeze-thaw cycle causing cracks in the rock. In contrast, the other options illustrate processes such as erosion, deposition, and chemical weathering, each distinct from the physical weathering process described in the correct answer. Understanding these differences is crucial in studying geological and environmental processes.

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