Chemical A is used for water softening to remove temporary hardness. A reacts with sodium carbonate to generate caustic soda. When CO_(2) is bubbled through a solution of A, it turns cloudy. What is the chemical formula of A ?

Chemical A is used for water softening to remove temporary hardness. A

1.	Chemical A is used for water softening to remove temporary hardness. A reacts with sodium carbonate to generate caustic soda. When CO_(2) is bubbled through a solution of A, it turns cloudy. What is the chemical formula of A ?
Answer» `CaCO_(3)` `CaO ` `Ca(OH)_(2)` `Ca(HCO_(3))_(2)` Solution :`underset("TEMP. HARDNESS")(Ca(HCO_(3))_(2)) +Ca(OH)_(2) to underset(A)(2CaCO_(3))darr +2H_(2)O` `underset((A))(Ca(OH)_(2)) +Na_(2) CO_(3) to underset("Caustic SODA")(CaCO_(3) darr )+ CaCO_(3)` `underset(A)(Ca(OH)_(2)) + CO_(2) to underset("Milkiness")(CaCO_(3)) darr +H_(2)O`