A water insoluble calcium compund (A) on reacting with dil. H2SO4 released a colourless and odourless gas, (B) with brisk effervescence .when gas B is passed through lime water,it turns milky and again formed a compound A. identify A,B and write a balanced chemical equation for the same.
Another equation for the reaction of lime water with carbon dioxide gas-
Ca(OH)2 + CO2 → CaCO3 + H2O