Match the extraction processes listed in column - I with metals listed in column - II:

Column- I	Column - II
A. Self reduction	P. Lead
B. Carbon reduction	Q. Silver
C. Complex formation and displacement of metal	R. Copper
D. Decomposition of iodide	S. Boron

1. Lead is extracted from its ore by reduction with carbon and a self-reduction process.

$\mathrm{PbO}+\mathrm{C}\to \mathrm{Pb}+\mathrm{CO}$

$\mathrm{PbS}+2\mathrm{PbO}⟶3 \mathrm{Pb}+{\mathrm{SO}}_2$

2. The process of extraction of the metal silver is called as cyanide process and sodium cyanide solution is used. In this a complex formation takes place and the metal is obtained by displacement.

${\mathrm{Ag}}_2 \mathrm{S}+4\mathrm{NaCN}\rightleftharpoons 2\mathrm{Na}\left[\mathrm{Ag}(\mathrm{CN}{)}_2\right]+{\mathrm{Na}}_2 \mathrm{S}$$\mathrm{Zn}+2\mathrm{Na}\left[\mathrm{Ag}(\mathrm{CN}{)}_2\right]\to {\mathrm{Na}}_2\left[\mathrm{Zn}(\mathrm{CN}{)}_4\right]+2\mathrm{Ag}$

3. Copper can be extracted in a similar process to lead.

4. As for boron, its iodide is unstable above a particular temperature. So crude metal is converted into its iodide (in a sealed container) and then the iodide is decomposed by heating to get pure metal.