Consider the following statements: Statement I: In the context of effect of water on rocks, chalk is known as a very permeable rock whereas clay is known as quite an impermeable or least permeable rock. Statement II: Chalk is porous and hence can absorb water. Statement III: Clay is not at all porous. Which one of the following is correct in respect of the above statements?

1. A. Both Statement II and Statement III are correct and both of them explain Statement I
2. B. Both Statement II and Statement III are correct but only one of them explains Statement I
3. C. Only one of the Statements II and III is correct and that explains Statement I
4. D. Neither Statement II nor Statement III is correct

Answer: C

Explanation

Statement I is correct: Chalk is indeed known for its high permeability, allowing water to pass through easily, while clay is characterized by its low permeability, making it largely impermeable to water. Statement II is correct: Chalk is highly porous, meaning it contains many small interconnected spaces. This porosity allows it to absorb and store water, which contributes to its high permeability. This statement correctly explains why chalk is permeable. Statement III is incorrect: Clay is porous; it has many tiny pore spaces between its very fine particles. However, these pores are often poorly interconnected or extremely small, resulting in very low permeability, meaning water struggles to flow through it despite its porosity. Therefore, Statement II is correct and explains Statement I, but Statement III is incorrect. Understanding rock properties like porosity and permeability is a fundamental concept in UPSC Geography and geology.