Chemistry PYQ 42 of 152 · Reactions & Catalysis

Limewater is turned milky by

  1. ACO
  2. BCO2
  3. CO2
  4. DO3
  5. ENone of the above / More than one of the above

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Correct answer: (b) CO2

Explanation

Limewater is a dilute solution of calcium hydroxide [Ca(OH)2].

CO2 reacts with it to form insoluble white calcium carbonate (CaCO3), turning it milky: Ca(OH)2 + CO2 → CaCO3 + H2O.

Gases like CO, O2 and O3 do not form this white precipitate.

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