S
Sahaj Vidhi
UPSC Prelim 2025 Paper I

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?

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

Explanation:

Statement I is correct: Chalk is permeable, and clay is impermeable. Statement II is correct: Chalk is porous and absorbs water, which explains its permeability. Statement III is incorrect: Clay is porous (it has voids and can hold water), but its very fine particle size and poor connectivity of pores make it impermeable, not non-porous. Therefore, only Statement II is correct among II and III, and it explains the permeability aspect of Statement I regarding chalk.