question_answer

  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. [NCERT Exemplar]

Answer:

               The gas evolved at anode during electrolysis of brine is chlorine (G). When chlorine gas is passed through dry Ca(OH)2 (Y) produces bleaching powder (Z) used for disinfecting drinking water. Since Y and Z are calcium salts, therefore X is also a calcium salt and is calcium carbonate. CaCO3 + 2HCl ® CaCl2 + CO2 + H2O Ca(OH)2 + CO2 ® CaCO3 + H2O