Explanation:

Solution refers to the weathering process in which the minerals of a rock get dissolved in some liquid (generally water or acid). Rain water in combination with atmospheric carbon dioxide forms weak carbonic acid. The limestone rocks are made up of calcium carbonate or calcium magnesium bicarbonate which are easily dissolved by the carbonic acid in the rain water. Further, limestone being a sedimentary rock is characterized by layers and empty pore spaces in its structure. Water can lodge in these pore spaces and speed up the solution process.