Transformation of feldspar into clay-like minerals is linked with which process?

Correct answer: Hydrolysis

The direct answer is A, hydrolysis. Hydrolysis is a type of chemical weathering in which water reacts with minerals and changes their chemical composition. Feldspar is a common rock-forming mineral. When water, often containing weak acids, reacts with feldspar, the original mineral structure breaks down and clay-like minerals are produced. The reasoning is: water enters cracks and mineral surfaces; it reacts with feldspar; the feldspar changes chemically; clay minerals and dissolved substances may result. Option A is correct because it names this exact chemical reaction. Option B, salt crystallisation, happens when dissolved salts grow as crystals in cracks and exert pressure; it mainly causes physical breaking, not feldspar-to-clay conversion. Option C, thermal fracture, occurs when repeated heating and cooling expand and contract rocks; it is mechanical weathering. Option D, frost action, occurs when water freezes, expands, and widens cracks; it is also physical weathering. The useful exam cue is: feldspar changing into clay means chemical weathering by hydrolysis. Do not confuse a chemical change in minerals with simple cracking of rocks.