How is chemical weathering different from physical weathering?
A. Chemical weathering forms new substances, while physical weathering does not. B. Chemical weathering involves plants and animals, while physical weathering does not. C. Chemical weathering requires a reaction with water, while physical weathering does not. D. Chemical weathering results in the breakdown of rock, while physical weathering does not.
The Correct Answer and Explanation is :
The correct answer is A. Chemical weathering forms new substances, while physical weathering does not.
Explanation
Weathering is the process that breaks down rocks and minerals at or near the Earth’s surface, and it can occur through two primary mechanisms: chemical weathering and physical weathering. Understanding the differences between these two processes is crucial for comprehending geological and environmental changes.
Chemical Weathering involves chemical reactions that alter the mineral composition of rocks, leading to the formation of new substances. This process often involves water, which acts as a solvent. For example, when carbon dioxide dissolves in rainwater, it forms carbonic acid, which can react with minerals like feldspar, transforming it into clay minerals and soluble ions. These reactions not only change the minerals present but also contribute to soil formation and nutrient cycling in ecosystems.
In contrast, Physical Weathering (or mechanical weathering) breaks rocks down into smaller pieces without altering their chemical composition. This can occur through various physical processes, such as freeze-thaw cycles, where water seeps into cracks in rocks, freezes, expands, and eventually causes the rock to fracture. Other physical weathering processes include thermal expansion and contraction, abrasion from wind or water, and biological activity, such as roots growing into cracks and splitting the rock apart.
While both types of weathering contribute to landscape changes and the breakdown of rocks, their mechanisms and outcomes differ significantly. Chemical weathering changes the material itself, often creating new mineral structures, while physical weathering retains the original mineral composition but reduces the size of rock particles. Together, these processes play vital roles in shaping the Earth’s surface, influencing soil formation, and impacting ecosystems. Understanding these distinctions helps us appreciate how geological and environmental changes occur over time.