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

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Q: (NDA-II/2019)

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

question_subject: 

Geography

question_exam: 

NDA-II

stats: 

0,14,15,14,5,5,5

keywords: 

{'calcium carbonate': [0, 0, 1, 4], 'limestone': [2, 0, 1, 0], 'chalk': [0, 0, 0, 3], 'marble': [2, 0, 0, 0], 'lime water': [0, 0, 0, 4], 'salt': [1, 0, 1, 1]}

The correct answer is option 1, Lime water. Lime water does not represent the salt Calcium carbonate.

Option 2, Limestone, does represent Calcium carbonate. Limestone is a sedimentary rock composed mainly of Calcium carbonate.

Option 3, Chalk, also represents Calcium carbonate. Chalk is a soft, white, porous form of limestone, which is also made up of Calcium carbonate.

Option 4, Marble, is another form of Calcium carbonate. Marble is a metamorphic rock formed from limestone that has undergone heat and pressure.

In contrast, Lime water refers to a solution of Calcium hydroxide (Ca(OH)2) in water, not Calcium carbonate. It is made by dissolving Calcium oxide (CaO) or Calcium hydroxide (Ca(OH)2) in water. Lime water is commonly used to test for the presence of Carbon dioxide (CO2) as it turns milky due to the formation of Calcium carbonate when Carbon dioxide is bubbled through it.

Therefore, option 1, Lime water, is the correct answer because it does not represent the salt Calcium carbonate unlike the other options.