The correct option is 2 and 3 only.
Explanation
Weathering is the action of elements of weather and climate over earth materials. It is broadly classified into chemical, physical (mechanical), and biological weathering. While physical weathering focuses on mechanical breakdown, chemical weathering involves the alteration of rock composition.
Statement-wise Analysis:
- Statement 1 is Incorrect: Chemical weathering involves the decomposition of rocks through chemical reactions such as solution, carbonation, hydration, and oxidation. It does not involve mechanical disintegration; mechanical disintegration is the defining characteristic of physical weathering.
- Statement 2 is Correct: Chemical weathering processes act on rocks to decompose, dissolve, or reduce them to a fine clastic state. Through chemical reactions involving oxygen, surface or soil water, and acids, the internal structure of minerals is altered, often resulting in fine-grained residues like clay.
- Statement 3 is Correct: In nature, chemical and physical weathering processes rarely operate in isolation. They often go hand-in-hand. Physical weathering increases the surface area of rocks, accelerating chemical reactions, while chemical weathering weakens the rock structure, facilitating further physical disintegration.
Key Takeaway:
The primary distinction in weathering processes is that physical weathering causes mechanical disintegration (breaking into smaller pieces), whereas chemical weathering causes decomposition (chemical alteration) of the rock material.