Lime water turns milky when carbon dioxide is passed through it. It is due to the formation of:

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RRB ALP CBT I 17 Aug 2018 Shift 2 Official Paper
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  1. Barium Carbonate
  2. Calcium Oxide
  3. Calcium Carbonate
  4. Calcium Hydrogen Carbonate

Answer (Detailed Solution Below)

Option 3 : Calcium Carbonate
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The correct answer is Calcium Carbonate.

Key Points

  •  Calcium Carbonate
    • A limestone is a form of calcium carbonate.
    • Other Different forms of calcium carbonate are Chalk and Marble.
    • Calcium carbonate is a chemical compound with the formula CaCO3.
    • It is a common substance found in rocks as the minerals calcite and aragonite (most notably as limestone, which is a type of sedimentary rock consisting mainly of calcite) and is the main component of eggshells, snail shells, sea shells, and pearls.

Additional Information

  • Barium Carbonate
    • Barium Carbonate (BaCO3) is a chemical compound Barium and Carbonate ions are chemically united in a fixed proportion. 
  • Calcium oxide
    • Calcium oxide is the chemical name of CaO.
    • Calcium oxide (CaO) compound is used as a drying agent.
    • The drying agent is used to remove water from an organic compound.
    • Calcium oxide is used to dry ammonia gas.
    • When Limestone (CaCO3) is heated, it gives Calcium oxide.
    • CaCO3 → CaO + Co2
    • It is also known as quick lime.
    • It is used for manufacturing cement, paper, Caustic Soda, etc.
  • Calcium Hydrogen Carbonate
    • Calcium bicarbonate is also known as Calcium Hydrogen Carbonate.
    • It has a chemical formula Ca(HCO3)2.
    • From the above formula, we can say calcium bicarbonate has 2 hydrogen atoms.
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