When water is added to compound (A) of calcium, solution of compound (B) is formed. When carbon dioxide is passed into the solution, it turns milky due to the formation of compound (C). If excess of carbon dioxide is passed into the solution milkiness disappears due to the formation of compound (D). Identify the compounds A, B, C and D. Explain why the milkiness disappears in the last step.

When water is added to compound (A) of calcium, solution of compound (

1.	When water is added to compound (A) of calcium, solution of compound (B) is formed. When carbon dioxide is passed into the solution, it turns milky due to the formation of compound (C). If excess of carbon dioxide is passed into the solution milkiness disappears due to the formation of compound (D). Identify the compounds A, B, C and D. Explain why the milkiness disappears in the last step.
Answer» Solution :SolutionB turns milky ion passing`CO_(2)`, it is lime WATER `Ca(OH)_(2)`and comound C which gives milky appearance is `CaCO_(3)`. On passing excess of `CO_(2)`milkinessdisappears due to the FORMATION of compound D that is `Ca(HCO_(3))_(2)`. Compound A REACTS with water and gives B. It is CaO. The reactions are : (i) `underset((A)) (CaO) +H_(2)O tounderset((B))underset("Lime water")(Ca(OH)_(2))` (ii)`underset((B))(Ca(OH)_(2))+underset((C ))underset(("Milky solution"))underset("Calcium carbonate")(CO_(2)+CaCO_(3)+H_(2)O)` (iii)On passing high amount of `CO_(2)` through calcium carbonate solution, it forms calcium BICARBONATE, which remove milky colour of solution. `underset((C ))underset("Milky colour")(CaCO_(3)) +CO_(2)+H_(2)O to underset((D))underset("(Soluble carbonate)")underset("Calcium carbonate")(Ca(HCO_(3))_(2))`