question_answer 78)

                  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 passed on dry Y, it gives a compound Z, used for disinfecting drinking water. Identify X, Y, G and Z.        

Answer:

  X is calcium carbonate and the gas evolved is carbon dioxide, when calcium carbon reacts with acid. Solution Y is lime waterbecause, whenis passed through it, it gives the carbonate back as shown by the given equation. The gas evolved at anode during electrolysis of brine is chlorine (G). When chlorine gas is passed through dry (Y), it produces bleaching powder (Z), used for disinfecting drinking water. Hence, Z is calcium oxy-chloride (CaOCl2) or bleaching powder.