Which pair lists two examples of chemical weathering?

Which pair lists two examples of chemical weathering?

• A. Oxidation (rust) and acid dissolution.
• B. Freeze-thaw cracking and abrasion.
• C. Erosion and deposition.
• D. Biological weathering such as root wedging.

Answer: (D)

Chemical weathering happens when minerals in rocks undergo chemical reactions that change their composition. Oxidation is a chemical reaction with oxygen that alters minerals (for example, iron-rich rocks forming rust). Acid dissolution occurs when acidic solutions (like carbonic acid from rain) dissolve minerals, altering the rock’s minerals and structure. These are chemical changes, not just physical breaks. Biological weathering such as root wedging is mainly physical: roots pry rocks apart as they grow, though biology can contribute some chemical effects, the primary impact is mechanical. Erosion and deposition involve moving rock and soil rather than changing the minerals in place, and freeze-thaw cracking is a physical process driven by expansion and contraction, not chemical alteration.

Chemical weathering happens when minerals in rocks undergo chemical reactions that change their composition. Oxidation is a chemical reaction with oxygen that alters minerals (for example, iron-rich rocks forming rust). Acid dissolution occurs when acidic solutions (like carbonic acid from rain) dissolve minerals, altering the rock’s minerals and structure. These are chemical changes, not just physical breaks.

Biological weathering such as root wedging is mainly physical: roots pry rocks apart as they grow, though biology can contribute some chemical effects, the primary impact is mechanical. Erosion and deposition involve moving rock and soil rather than changing the minerals in place, and freeze-thaw cracking is a physical process driven by expansion and contraction, not chemical alteration.