Consider the following pairs: I. Solution : results in leaching of minerals II. Carbonation : helps in breaking down of feldspar III. Hydration : causes increase in volume of rocks IV. Oxidation : causes change in colour of rocks. How many of the above pairs are correctly matched?

All four pairs correctly describe types of chemical weathering. (I) Solution dissolves soluble minerals (e.g., salts, gypsum) and leaches them out — correct. (II) Carbonation, the reaction of CO2-charged water with minerals, is particularly effective in breaking down feldspar (in granite) into clay minerals — correct. (III) Hydration involves absorption of water by minerals (e.g., anhydrite → gypsum), causing volumetric expansion and disintegration of rock — correct. (IV) Oxidation, especially of iron-bearing minerals, produces reddish-brown iron oxides changing rock colour — correct. Hence all four are correctly matched.