Question

Arrange the following materials in decreasing order of their porosity (percentage of total volume of material that consists of pore spaces): A. Sand B. Clay C. Gravel D. Sandstone (Semi consolidated)

• A. D, C, A, B
• B. B, A, C, D
• C. A, B, C, D
• D. B, A, D, C

Hint:

Clay has the highest porosity due to fine particles, while semi-consolidated sandstone has the lowest due to cementation.

Answer 1

The Correct Option is B

Step 1: Concept
Porosity --- the percentage of total volume of a material that consists of pore spaces.

Step 2: Meaning
Porosity depends on particle size, shape, and packing. Smaller particles can have higher total void space.

Step 3: Analysis
Typical porosity values: Clay ($\sim$45--55%) $>$ Sand ($\sim$25--50%) $>$ Gravel ($\sim$25--40%) $>$ Sandstone/semi-consolidated ($\sim$10--20%). Clay has the highest porosity due to its very fine, platy particles creating numerous small pores. Sandstone has the lowest among these due to cementation between grains.

Step 4: Conclusion
In decreasing order of porosity: Clay (B) $>$ Sand (A) $>$ Gravel (C) $>$ Sandstone (D). Final Answer: (B)