The most important chemical weathering process of rock is

Correct option is C

The correct answer is (C) Hydrolysis

Explanation:
• Chemical weathering is the decomposition of rocks through chemical reactions that change the mineralogy. Hydrolysis is considered the most important process in soil formation (pedogenesis).
• Hydrolysis involves the reaction between water (specifically $H^+$ and $OH^-$ ions) and the minerals in the rock.
• During hydrolysis, the hydrogen ions replace the basic cations (like $K^+$, $Na^+$, $Ca^{2+}$) in the mineral structure. This leads to the complete breakdown of primary minerals like feldspars and the formation of new secondary minerals like clay (Kaolinite).
• Example: $Orthoclase + Water ightarrow Kaolinite + Silicic Acid + Potassium Hydroxide$.

Information Booster:
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• Without hydrolysis, the formation of clay minerals, which are essential for soil fertility and water retention, would be significantly reduced.
• Water acts not just as a solvent but as a chemical reactant in this process.

Additional Knowledge:
• Solution (Option A): Dissolving soluble minerals like Halite ($NaCl$) or Gypsum in water.
• Hydration (Option B): The physical attachment of water molecules to a mineral structure (e.g., Hematite to Goethite).
• Oxidation (Option D): Reaction of minerals with oxygen, important for iron-rich rocks (causing 'rusting').