Limestone is a hard rock composed mostly of what?

Prepare for the AIT Welder 2nd Period Exam. Study with flashcards and multiple-choice questions, each question includes hints and explanations. Ensure your readiness for the AIT Welder examination!

Multiple Choice

Limestone is a hard rock composed mostly of what?

Explanation:
Limestone is composed mainly of calcium carbonate, typically present as calcite, with some rocks also containing dolomite when magnesium substitutes for calcium (giving CaMg(CO3)2). This carbonate-rich makeup explains its hardness, how it can react with acidic solutions to fizz, and its common uses in cement and lime production. The other substances listed—silicon dioxide, aluminum oxide, and magnesium sulfate—do not constitute limestone’s primary mineral content. Silicon dioxide is the main component of quartz and many sands, aluminum oxide appears in bauxite and some clays, and magnesium sulfate is an evaporite mineral unrelated to limestone’s carbonate composition.

Limestone is composed mainly of calcium carbonate, typically present as calcite, with some rocks also containing dolomite when magnesium substitutes for calcium (giving CaMg(CO3)2). This carbonate-rich makeup explains its hardness, how it can react with acidic solutions to fizz, and its common uses in cement and lime production. The other substances listed—silicon dioxide, aluminum oxide, and magnesium sulfate—do not constitute limestone’s primary mineral content. Silicon dioxide is the main component of quartz and many sands, aluminum oxide appears in bauxite and some clays, and magnesium sulfate is an evaporite mineral unrelated to limestone’s carbonate composition.

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