Which Rocks term is correctly associated with common use or association: “used as an abrasive and lightweight aggregate”, and also with “a vesicular volcanic rock”?

Correct Answer: Option D — Pumice. Pumice is correct because it is used as an abrasive and lightweight aggregate. Pumice is also associated with a vesicular volcanic rock. A further identifying fact is that Pumice is so porous that some pieces can float on water. Another useful fact is that Pumice is associated with used as an abrasive and lightweight aggregate. Why the other options are incorrect: Option A — Obsidian: It is historically used for sharp cutting tools and is associated with a volcanic glass; those are the identifying facts of Obsidian. Option B — Sandstone: It is commonly used as a building stone and is associated with a clastic sedimentary rock; those are the identifying facts of Sandstone. Option C — Limestone: It is a major raw material for cement and is associated with a sedimentary carbonate rock; those are the identifying facts of Limestone. Exam Takeaway: Link Pumice with “used as an abrasive and lightweight aggregate” and “a vesicular volcanic rock” for quick revision.