A teacher investigates the reactions of copper carbonate, CuCO3\text{CuCO}_3CuCO3.
The diagram shows the reactions the teacher does.

State the name of the soluble salt, X.
State the name of gas Y.
Gas Z relights a glowing splint. State the name of gas Z.
The teacher performs a flame test of the copper made by the electrolysis of X. What colour flame does the teacher observe?
Copper metal is extracted from copper oxide by heating with carbon as shown in the equation:
copper oxide+carbon→copper+carbon dioxide\text{copper oxide} + \text{carbon} \rightarrow \text{copper} + \text{carbon dioxide}copper oxide+carbon→copper+carbon dioxide
Explain why copper is extracted. Use ideas about the reactivity series.
Copper is used to make useful alloys. Complete the table below by identifying the missing metals or uses.
| Alloy | Main metals | Uses |
|---|---|---|
| brass | copper and ......................... | musical instruments |
| cupronickel | copper and ......................... | coinage |
| bronze | copper and tin | ......................... |