A metal carbonate X on reacting with an acid gives a gas which when passed through a solution Y gives the carbonate back. On the other hand, a gas G that is obtained at anode during electrolysis of brine is passed on dry Y, it gives a compound Z, used for disinfecting drinking water . Identify X,Y,G and Z.

Explanation

X is calcium carbonate and the gas evolved is carbon dioxide when calcium carbonate reacts with acid .
`CaCO_(3)+"Dil."2HClrarrCaCl_(2)+H_(2)O+CO_(2)uparrow`
Solution Y is lime water `Ca(OH)_(2)+CO_(2)rarrCaCO_(3)downarrow+H_(2)O`
The gas evolved at anode during electrolysis of brine is chlorine (G)
`2NaCl+2H_(2)Orarr2NaOH+Cl_(2)(g)+H_(2)(g)`
When chlorine gas is passed through dry `Ca(OH)_(2)(Y)`, it produces bleaching powder (Z) used for disinfecting drinking water .
`Ca(OH_(2))+Cl_(2)rarrCaOCl_(2)+H_(2)O`
Hence Z is calcium oxy chloride `(CaOCl_(2))` or bleaching powder.