A compound X on heating gives a colourless gas. This residue is dissolved in water to obtain Y. excess `CO_(2)` is bubbled through aqueous solution of Y, Z is formed. Z on gentle heating give back X. the X is

Options

A. `CaCO_(3)`
B. `Ca(HCO_(3))_(2)`
C. `NaHCO_(3)`
D. `Na_(2)CO_(3)`

Answer

A

Explanation

`{:(underset([X])(CaCO_(3))overset(Delta)rarrCO_(2)+CaOoverset(H_(2)O)rarr,underset([Y])(Ca(OH)_(2))),(,Co_(2)darr"excess"),(" "underset([X])(CaCO_(3))darroverset(Delta)larr,underset([Z])(Ca(HCO_(3))_(2))):}`