Q.Starting with sodium chloride how would you proceed to prepare

1. Sodium metal Electrolyse fused (molten) NaCl (Down's process); Na metal is deposited at the cathode and Cl$_2$ is liberated at the anode:

   $2NaCl \xrightarrow{\text{electrolysis, molten}} 2Na + Cl_2\uparrow$

2. Sodium hydroxide Electrolyse a concentrated aqueous solution of NaCl (chlor-alkali/Castner–Kellner process); NaOH is formed at the cathode compartment along with H$_2$, with Cl$_2$ liberated at the anode:

   $2NaCl(aq) + 2H_2O \xrightarrow{\text{electrolysis}} 2NaOH + Cl_2\uparrow + H_2\uparrow$

3. Sodium peroxide Starting from the sodium metal obtained in (i), burn it in a free/excess supply of dry oxygen:

   $2Na + O_2 \xrightarrow{\Delta} Na_2O_2$

4. Sodium carbonate Either pass CO$_2$ into the NaOH solution obtained in (ii): …

Treat NaCl as the common starting material and derive each target compound with the shortest correct industrial/laboratory route: fused-salt electrolysis for the metal, aqueous electrolysis for the hydroxide, direct combustion of the metal in exces …

• Using aqueous electrolysis to try to obtain free Na metal — this liberates H$_2$ at the cathode, not Na, because Na$^+$ is not reduced in preference to water.
• Burning sodium in a limited supply of air/oxygen and expecting Na$_2$O$_2$ — a restricted oxygen supply favours Na$_2$O, not the peroxide. …