Question

(3) as this weak acid soaked downward, it dissolved some of the calcium in the shells, producing calcium carbonate, which solidified in lower layers, much like how flowstone and stalactites are formed in caves. this material \glued\ the shell fragments together into a porous type of limestone we now call coquina, which is spanish for \tiny shell.\ based on paragraph 3, what is true about calcium carbonate? a. it dissolves calcium in shells. b. it solidifies when placed in caves. c. it is made from limestone. d. it helps bond materials together.

Explanation:

• Option A: The weak acid dissolves calcium in shells to produce calcium carbonate, not calcium carbonate dissolving calcium in shells. Eliminate A.
• Option B: The text says calcium carbonate solidified in lower layers (similar to flowstone/stalactites formation in caves), but it doesn't state it solidifies "when placed in caves" (the context is about its formation in the process of shell fragments bonding, not about placing it in caves). Eliminate B.
• Option C: Coquina (the porous limestone) is made with shell fragments and calcium carbonate, but the text doesn't say calcium carbonate is made from limestone. Eliminate C.
• Option D: The text states "This material ('this material' refers to calcium carbonate) 'glued' the shell fragments together", and "glued" means bonding materials. So D is correct.

Answer:

D. It helps bond materials together.