The weathering process which is commonly found in limestone regions is

1. Analyze the question You're asked which weathering process is typical of limestone regions. Limestone is made mostly of calcium carbonate (CaCO₃), so the answer depends on how this mineral reacts with water.

2. Explain the concept Look at each option:

• Hydrolysis: a chemical reaction between water and minerals, mostly feldspar in rocks like granite. It turns feldspar into clay (kaolin). It is not typical of limestone.
• Exfoliation: a physical (mechanical) process where outer layers peel off like onion skins. It is caused by repeated heating and cooling, mostly in bare rocks in deserts. It is not chemical and is not specific to limestone.
• Oxidation: the reaction of oxygen with iron-bearing minerals, which produces rust-coloured staining. It is not typical of limestone.
• Solution (carbonation-solution): rainwater absorbs carbon dioxide and becomes weak carbonic acid. This acid dissolves calcium carbonate:

CaCO₃ + H₂O + CO₂ → Ca(HCO₃)₂ (calcium hydrogen carbonate, which is soluble and washes away)

3. Solution Limestone is attacked by slightly acidic rainwater, which dissolves it. This creates features of limestone (karst) landscapes such as:

• Caves and caverns
• Sinkholes (swallow holes)
• Stalactites and stalagmites
• Limestone pavements (clints and grikes)

These are all the results of dissolving the rock, so the process is solution.

4. Answer The correct option is D. solution.

5. Exam tip Link rock to process:

• Limestone → solution/carbonation ("lime = dissolve")
• Granite → hydrolysis
• Iron-rich rocks → oxidation
• Bare rocks in deserts → exfoliation

Whenever you see "limestone" in a weathering question, think of carbonic acid and dissolving.