Q. 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?
(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
Correct Answer: (c) Only one of the Statements II and III is correct and that explains Statement I.
UPSC Prelims 2025 GS Paper's Solution
Explanation :
Rocks, Clay, Chalk
Statement I is correct. Chalk is indeed known as a highly permeable rock, while clay is considered relatively impermeable or least permeable.
Statement II is correct. Chalk is porous, meaning it contains numerous tiny spaces or pores within its structure. Due to this porosity, chalk can absorb and allow water to pass through it, making it permeable.
Statement III is incorrect. Clay, although impermeable or least permeable, is actually porous. Clay has very fine pores, but due to their extremely small size and the nature of clay particles, water cannot easily pass through. Thus, clay is porous but impermeable because the pores are too small to allow water to flow freely.
Therefore, Statement II correctly explains Statement I, while Statement III is incorrect. Hence, option (c) is the correct choice.
