UPSC CSE Prelims
Question 3
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?
View correct answer and explanation
Correct answer: C
Correct Option: C (Only one of the Statements II and III is correct and that explains Statement I)
Explanation: Only Statement II correctly explains the contrast: porous, fractured chalk can transmit and store groundwater. Clay generally has very low permeability because its pore spaces are tiny and poorly connected, but it is not completely non-porous.
Statement / Pair / Item-wise Analysis:
Statement I: Correct-chalk is relatively permeable, clay has low permeability.
II: Correct-chalk's pores help water enter and flow through it.
III: Incorrect-clay is porous, though its permeability is low.
Option-wise Analysis:
A. Incorrect-this wrongly treats both supporting statements as valid or assigns an incorrect explanatory relationship.
B. Incorrect-this wrongly treats both supporting statements as valid or assigns an incorrect explanatory relationship.
C. Correct-this matches the facts and the item-wise assessment above.
D. Incorrect-omits I which the answer requires.