Question 68
Set 4
Contents
QQuestion
OOptions
✓Correct Answer
DDalvoy Solutions
Statement I: Correct. Chalk is indeed very permeable (allows water to pass through) while clay is quite impermeable (prevents water movement).
Statement II: Correct and explains Statement I. Chalk is porous with numerous interconnected pore spaces that allow water absorption and movement, making it highly permeable despite being a solid rock.
Statement III: Incorrect. Clay is actually quite porous, but its pores are extremely small (micropores) and poorly connected, which prevents water movement. It's the size and connectivity of pores, not the absence of porosity, that makes clay impermeable.
Only Statement II correctly explains the permeability difference, as chalk's effective porosity allows water flow while clay's microporous structure restricts it.
SUPSC Prelims Strategy and Tips
For rock permeability questions, distinguish between porosity (presence of pores) and permeability (ability for fluids to flow). A rock can be porous but still impermeable if pores are not well-connected.