A metal carbonate

X is calcium carbonate. When calcium carbonate reacts with acid such as hydrochloric acid, carbon dioxide is released.

Solution Y is lime water [Ca(OH)₂ ]. When CO₂ is passing through lime water, it turns milky due to the formation of calcium carbonate.

During electrolysis of brine, chlorine (G) gas is deposited at anode.

When chlorine gas is passed through dry slaked lime Ca(OH)₂ (Y), it produces bleaching powder (Z). Bleaching powder is used for disinfecting drinking water.

Ca(OH) + Cl₂ CaOCl₂ + H₂O

Hence, Z is calcium oxychloride (CaOCl₂) or bleaching powder.

To sum up,

1. Metal carbonate (X) is calcium carbonate.

2. Solution (Y) is lime water (calcium hydroxide).

3. Gas (G) is chlorine gas.

4. Dry (Y) is dry calcium hydroxide (dry slaked lime).

5. Compound (Z) is bleaching powder (calcium oxychloride).