The correct answer is Salt crystal growth .

The correct answer to the given question is option 2, Salt crystal growth, which is not a type of chemical weathering.

Chemical weathering is the process of breaking down rocks and minerals through chemical reactions, resulting in the formation of new compounds. The four common types of chemical weathering are:

Carbonation: This process occurs when carbon dioxide gas in the atmosphere dissolves in water, forming carbonic acid. The acid then reacts with minerals in the rock, such as calcium carbonate, to form new compounds like calcium bicarbonate, which are more soluble in water and can be easily transported away.

Salt crystal growth: This is not a type of chemical weathering. Salt crystal growth occurs when saltwater seeps into rocks and evaporates, leaving behind salt crystals. These crystals can grow and cause physical stress on the rock, leading to mechanical weathering.

Hydrolysis: This process occurs when water reacts with minerals in the rock, leading to the formation of new compounds. For example, feldspar minerals in granite can be hydrolyzed to form clay minerals.

Oxidation: This process occurs when oxygen reacts with minerals in the rock, resulting in the formation of new compounds. For example, iron in minerals like pyrite and olivine can be oxidized to form iron oxides like rust.

In conclusion, salt crystal growth is not a type of chemical weathering. The other three options mentioned – Carbonation, Hydrolysis, and Oxidation are types of chemical weathering processes that occur in nature.