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, when a gas G 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

When calcium carbonate reacts with hydrochloric acid, it gives carbon dioxide gas.
${CaCO}_3+2HCl\to {CaCl}_2+{CO}_2+H_{2}O$

When carbon dioxide is passed through limewater, the limewater turns milky. This happens because of the formation of calcium carbonate.
${CO}_2+Ca(OH{)}_2\to {CaCO}_3+H_{2}O$

On electrolysis of brine, chlorine gas is obtained at the anode. When chlorine gas is passed through limewater, it gives bleaching powder.
$Ca(OH{)}_2+{Cl}_2\to {CaOCl}_2+H_{2}O$

X is calcium carbonate. Y is limewater. G is chlorine. Z is bleaching powder.