Question

1. distinguish between the characteristics of an unweathered rock and those of a highly weathered rock. 2. describe the factors that control the rates of chemical weathering and those of physical weathering. 3. compare chemical weathering to mechanical weathering.

Explanation:

1. An unweathered rock is typically smooth, with sharp edges and uniform color, while a highly - weathered rock has a rough surface, rounded edges, and may show color variations due to chemical changes.
2. For chemical weathering, factors like temperature, moisture, presence of acids (e.g., from rain or biological sources) control the rate. For physical weathering, factors include temperature changes (freeze - thaw cycles), abrasion from wind or water, and pressure release.
3. Chemical weathering involves chemical reactions that change the rock's composition, like oxidation or dissolution. Mechanical (physical) weathering breaks the rock into smaller pieces without changing its chemical composition, such as through frost wedging.

Answer:

1. An unweathered rock has smooth surfaces, sharp edges, and uniform color. A highly - weathered rock has rough surfaces, rounded edges, and color variations.
2. Chemical weathering rates are controlled by temperature, moisture, and presence of acids. Physical weathering rates are controlled by temperature changes, abrasion, and pressure release.
3. Chemical weathering changes rock composition via reactions. Mechanical weathering breaks rock physically without changing composition.