Detailed Explanation:

Correct Answer: ✅ Option 3

Chalk and clay differ mainly in permeability, not simply in porosity. Chalk contains many interconnected pores, allowing water to pass through easily. Clay also has pores, but they are extremely small and poorly connected, so water movement is very slow. Therefore, Statement II is correct and explains Statement I, while Statement III is incorrect.

✅ Statement I is Correct: Chalk is highly permeable, whereas clay is one of the least permeable rocks/soils.

✅ Statement II is Correct: Chalk is porous and can absorb and transmit water through its interconnected pore spaces.

❌ Statement III is Incorrect: Clay is not non-porous; it is porous but has very tiny pores that restrict water movement.

Short Notes: Porosity and Permeability

• Porosity is the percentage of pore spaces in a rock or soil.

• Permeability is the ability of water to move through those pore spaces.

• A rock can be porous but impermeable if pores are not well connected.

• Chalk is both porous and permeable.

• Clay is porous but largely impermeable due to tiny pore size.

• Groundwater is commonly stored in porous and permeable rocks called aquifers.

• Sandstone and chalk are common aquifer rocks.