(a) Sodium carbonate ${\mathrm{Na}}_2{\mathrm{CO}}_3$ & ${\mathrm{NaHCO}}_3$ are prepared by Solvay process.

(b) Titanium is refined by Van-Arkel process.

Titanium : Van arkel method

${\mathrm{T}}_{\mathrm{i}}+{\mathrm{I}}_2\stackrel{\mathrm{T}1}{⟶}{\mathrm{T}}_{\mathrm{i}}\underset{\left(\mathrm{g}\right)}{{\mathrm{I}}_4}$

${\mathrm{T}}_{\mathrm{i}}\underset{\left(\mathrm{g}\right)}{{\mathrm{I}}_4}\underset{{\mathrm{T}}_2>{\mathrm{T}}_1}{\overset{{\mathrm{T}}_2}{\to }}\underset{\mathrm{Refined} \mathrm{titanium}}{{\mathrm{T}}_{\mathrm{i}}}+2\underset{\left(\mathrm{g}\right)}{{\mathrm{I}}_2}$

(c) Chlorine is prepared by Deacon process.

Chlorine : Decon's process

$\mathrm{HCl}+{\mathrm{O}}_2\stackrel{{\mathrm{CuCl}}_2}{⟶}{\mathrm{H}}_2\mathrm{O}+{\mathrm{Cl}}_2$

(d) Sodium hydroxide is prepared by Castner - Kellner process.