Which one of the following is not an example of chemical weathering?

Weathering is categorized into physical (mechanical) and chemical processes. Chemical weathering involves the decomposition of rocks through chemical reactions that alter their mineral composition. Key examples include hydrolysis, where minerals react with water to form new substances like clay; oxidation, where oxygen reacts with metallic elements to form oxides like rust [2]; and acid action (acidification), often involving carbonic acid or acid rain that dissolves minerals. In contrast, salt crystal growth (also known as haloclasty) is a form of physical or mechanical weathering [3]. It occurs when saline solutions seep into rock crevices and evaporate, leaving behind crystals that expand upon heating or further crystallization [1]. This expansion exerts physical pressure on the rock walls, leading to granular disintegration without altering the rock's internal chemical structure [4].

Sources

1. [2] Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 4: Weathering, Mass Movement and Groundwater > CHEMICAL WEATHERING > p. 37
2. [3] https://www.sciencedirect.com/science/article/abs/pii/S0013795225000857
3. [1] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 6: Geomorphic Movements > Salt Weathering > p. 85
4. [4] https://education.nationalgeographic.org/resource/weathering/