Question

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 the anode during electrolysis of brine is passed on dry Y, it gives a compound Z, used for disinfecting drinking water. Identity X, Y, G and Z

Answer 1

• 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. 

Ca(OH)₂ + Cl₂ → CaOCl₂ + H₂O 

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 → CaCO₂ + H₂O