Which method does NOT contribute to the physical weathering of soil?

• A. Physical abrasion
• B. Thermal expansion
• C. Pressure release
• D. Chemical alteration

Answer: (D)

The process of physical weathering involves the mechanical breakdown of rocks and soils without changing their chemical composition. The correct answer identifies a method that does not fit this definition.

Chemical alteration involves the alteration of the chemical structure of minerals in soil or rock, leading to the formation of new minerals and compounds. This process includes reactions such as hydrolysis, oxidation, and carbonation, which fundamentally change the original materials at a molecular level. Therefore, it is not considered a method of physical weathering.

In contrast, physical abrasion refers to the wearing down of surfaces through friction, thermal expansion involves changes in volume and stress on materials due to temperature fluctuations, and pressure release involves the fracturing of rocks when they are exposed to lower pressure (such as when overlying materials are removed). All these processes contribute to the mechanical breakdown and disintegration of soil and rock materials.