(i) Role of NaCN in the extraction of silver is to do the leaching of silver ore in the presence of air from which the silver is obtained later by replacement $\begin{array}{l}4\text{A}\text{g}(\text{s})+8\text{C}{\text{N}}^{-}(\text{a}\text{q})+2{\text{H}}_2\text{O}(\text{a}\text{q})+{\text{O}}_2(\text{g})\to {\left[\text{A}\text{g}{(\text{C}\text{N})}_2\right]}^{-}(\text{a}\text{q})+4\text{O}{\text{H}}^{-}(\text{a}\text{q})\\ 2{\left[\text{A}\text{g}{(\text{C}\text{N})}_2\right]}^{-}(\text{a}\text{q})+\text{Z}\text{n}(\text{s})\to 2\text{A}\text{g}(\text{s})+{\left[\text{Z}\text{n}{(\text{C}\text{N})}_4\right]}^{2-}(\text{a}\text{q})\end{array}$

(ii) $\text{Ti}+{\text{I}}_2\underset{}{\stackrel{\text{Δ}}{\to }}{\text{TiI}}_4\stackrel{\text{Δ}}{\to }\text{Ti}+{\text{I}}_2$ (Van-Arkel method)
(iii) In the metallurgy of aluminium, cryolite lowers the melting point of the mixture and improves the electrical conductivity of the cell.