Which of the  following processes is/are the examples of leaching

$\left(I\right)$ Mac Aurthur forest process

$\left(II\right)$ Hoop's process

$\left(III\right)$ Baeyer's process

$\left(IV\right)$ Serpeck's process

$\left(I\right)$ In Mac Arthur forest process, silver ore is leached out as 

${\left[\mathrm{Ag}{\left(\mathrm{CN}\right)}_2\right]}^{-}$${\mathrm{Ag}}_2\mathrm{S}+\mathrm{NaCN}\stackrel{\mathrm{air}}{\rightleftharpoons } 2{\left[\mathrm{Ag}{\left(\mathrm{CN}\right)}_2\right]}^{-}+2{\mathrm{Na}}^{+}{\mathrm{Na}}_2\mathrm{S}$

$\left(II\right)$ In Baeyer's process, alumina and ${\mathrm{SiO}}_2$ is leached out as ${\left[\mathrm{Al}{\left(\mathrm{OH}\right)}_4\right]}^{-}$ and ${\mathrm{Na}}_2{\mathrm{SiO}}_3$ respectively

$\left(III\right)$ Hoop's process is for purification of Aluminium

$\left(IV\right)$ In Serpeck's process bauxite is heated with coke in the presence of  gas hence it is not an example of leaching as it does not occur in aqueous medium