The pourbaix diagram is of great value in selecting the solution conditions necessary not only for the dissolution of solid minerals but equally for precipitation of solid phase from the process liquor or leach liquor. In light of that, utilise the Eh$-$pH diagram presented in figure $1$ below to answer the following questions;

a$)($i$)$ Identify and label all possible reaction paths that may be used to dissolve material consisting of copper oxide. $[5]$

$($ii$)$ For each reaction path, provide the relevant chemical equations. $[5]$

$($iii$)$ Indicate whether each selected reaction path is oxidative, reductive or

chemical. $[5]$

b$)$ Copper $($II$)$ salts have been widely used as oxidizing agents in hydrometallurgy. Choose one example where there are used for leaching application and give a

detailed account of the process. $[15]$