Answer :
Final answer:
The statement is true; limestone is mainly made of calcite and can form through biogenic accumulation of marine organisms or by inorganic processes such as mineral precipitation.The answer is d) This statement is completely true.
Explanation:
The statement "Limestone is composed mainly of calcite and can form by both inorganic and biologic processes" is completely true. Limestone, being a type of rock consisting mostly of calcium carbonate (CaCO3), forms through various processes. The biogenic process includes the accumulation and compacting of marine organisms' remains, such as shells and skeletons, which secrete calcite. Equally, chemical limestone can form inorganically when minerals precipitate from water with dissolved calcium and bicarbonate ions, resulting in the formation of calcite without direct biological influence.
Several forms of limestone exist; there's biogenic limestone, which includes shells or reefs from calcite-secreting organisms, as well as chemical limestone. There are also types like chalk and coquina, which are composed of microfossils or clasts of shells, respectively, and both react to acid due to their calcite content. All these details confirm that limestone's composition and formation indeed align with both biologic and inorganic natural processes.
