Rainfall is one of the reasons for weathering of rocks

Answer: (a) Both Statement-II and Statement-III are correct and both of them explain Statement-I

Topic: Geography – Geomorphic Processes

Explanation: Weathering is an essential process that helps shape and change landscapes over time. There are many different factors that contribute to weathering, such as wind, rain, temperature changes, and more. hence, Statement-I is correct.

Rainwater can weather rocks through chemical weathering, a process that occurs when rainwater’s chemicals react with minerals in the rock. Rainwater contains carbon dioxide from the air, which makes it slightly acidic. When this acidic water comes into contact with minerals in the rock, it can cause a reaction that forms new minerals and soluble salts. This process is the first step in the creation of soil. Hence, Statement-II is correct and correctly explains Statement-I.

From NCERT again: A group of weathering processes viz; solution, carbonation, hydration, oxidation and reduction act on the rocks to decompose, dissolve or reduce them to a fine clastic state through chemical reactions by oxygen, surface and/or soil water and other acids. Water and air (oxygen and carbon dioxide) along with heat must be present to speed up all chemical reactions. Over and above the carbon dioxide present in the air, decomposition of plants and animals increases the quantity of carbon dioxide underground. These chemical reactions on various minerals are very much similar to the chemical reactions in a laboratory.

Source(s): NCERT Geography Textbook: Chapter 6 Geomorphic Processes

Difficulty level: Easy as straight forward from NCERT Textbook