A compound A on heating gives a colourless gas and a residue that is dissolved in water to obtained B . Excess of CO_(2) is bubbled through aqueous solution of B , C is formed which is recovered in the solid form . Solid C on gentle heating gives back A . The compound is

A compound A on heating gives a colourless gas and a residue that is d

1.	A compound A on heating gives a colourless gas and a residue that is dissolved in water to obtained B . Excess of CO_(2) is bubbled through aqueous solution of B , C is formed which is recovered in the solid form . Solid C on gentle heating gives back A . The compound is
Answer» `CaCO_(3)` `Na_(2)CO_(3)` `K_(2)CO_(3)` `CaSO_(4) . 2 H_(2)O` Solution :`underset((A))(CaC)O_(3)(s) overset(Delta)(to) CO_(2) (g) + CaO(s)` `CaO (s) + H_(2)O (l) to underset((B))(Ca(OH)_(2)) (aq)` `underset((B)) (Ca(OH)_(2)) (aq) + underset(("excess"))(2 CO_(2)) (g) to Caunderset((C))((HCO_(3))_(2)) (aq) ` `Caunderset((C))((HCO_(3))_(2)) (aq) overset(Delta)(to) Ca underset((A))(CO_(3)) (s) + CO_(2) (g) + H_(2)O(l)`