Which one of the following does not represent the salt, Calcium carbon

Which one of the following does not represent the salt, Calcium carbonate ?

Lime water
Limestone
Chalk
Marble
This question was previously asked in
UPSC NDA-2 – 2019
Calcium carbonate ($\text{CaCO}_3$) is a common chemical compound found in various natural forms. Limestone, chalk, and marble are all naturally occurring forms of calcium carbonate. Limestone is a sedimentary rock largely composed of calcium carbonate. Chalk is a type of limestone. Marble is a metamorphic rock formed from limestone.
Lime water, however, is a saturated solution of calcium hydroxide ($\text{Ca(OH)}_2$). It is produced by dissolving calcium oxide (quicklime) in water to form calcium hydroxide (slaked lime), and then dissolving the calcium hydroxide in more water. While calcium carbonate can be *formed* by passing carbon dioxide through lime water (causing precipitation), lime water itself is calcium hydroxide solution, not calcium carbonate.
– Calcium carbonate ($\text{CaCO}_3$) exists in forms like limestone, chalk, and marble.
– Lime water is a solution of calcium hydroxide ($\text{Ca(OH)}_2$).
– Passing $\text{CO}_2$ through lime water produces $\text{CaCO}_3$ precipitate.
Calcium carbonate is a widely used substance, for example, as a building material, as an abrasive, in agriculture to reduce soil acidity, and in medicine as an antacid. Calcium hydroxide (lime water) is also used in various industrial processes and as a test for carbon dioxide.
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