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UPSC 2025: 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
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Not attemptedCorrect Answer: (c) Only one of the Statements II and III is correct and that explains Statement I
Chalk is highly porous (35-47 % porosity) and, because its pore spaces are well connected, it is very permeable and can readily absorb water ([en.wikipedia.org](https://en.wikipedia.org/wiki/Chalk?utm_source=openai)). Clay, however, though quite porous, has extremely small, poorly connected pores so its permeability is minimal; it is therefore misleading to say it is ‘not at all porous’ ([opentextbc.ca](https://opentextbc.ca/physicalgeology2ed/chapter/14-1-groundwater-and-aquifers/?utm_source=openai)). Hence Statement II alone is correct and it fully explains Statement I, while Statement III is incorrect.
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Frequently Asked Questions
What is the correct answer to this UPSC 2025 Geography question?▼
The correct answer is option (c): Only one of the Statements II and III is correct and that explains Statement I. Watch the detailed video explanation in our Sherlocking Prelims course on UnlockIAS.
Which year was this Physical Geography & Geomorphology question asked in UPSC Prelims?▼
This question was asked in UPSC CSE Prelims 2025, GS Paper 1, as Question 28. It falls under Geography > Physical Geography & Geomorphology.
What is the difficulty level of this UPSC question?▼
This question is rated "moderate". It requires sound conceptual understanding of the topic.
How many UPSC Prelims questions have been asked from Physical Geography & Geomorphology?▼
UPSC has asked 25 questions from Physical Geography & Geomorphology (under Geography) across multiple years. Visit the topic page to see the full list and year-wise trends.