A-II; B-IV; C-III; D-I

A-II; B-IV; C-I; D-III

A-IV; B-I; C-II; D-III

A-III; B-II; C-I; D-IV

oxides of Cu and Fe

carbonates of Cu and Fe

sulphides of Cu and Fe

silicates of Cu and Fe

$2 \mathrm{Cu}_{2} \mathrm{~S}+3 \mathrm{O}_{2} \xrightarrow{\Delta} 2 \mathrm{Cu}_{2} \mathrm{O}+2 \mathrm{SO}_{2} \uparrow$

$\mathrm{Al}_{2} \mathrm{O}_{3}(\mathrm{~s})+2 \mathrm{NaOH}(a q)+3 \mathrm{H}_{2} \mathrm{O}(l) \rightarrow 2 \mathrm{Na}\left[\mathrm{Al}(\mathrm{OH})_{4}\right](a q)$

$2 \mathrm{CuFeS}_{2}+\mathrm{O}_{2} \rightarrow \mathrm{Cu}_{2} \mathrm{~S}+2 \mathrm{FeS}+\mathrm{SO}_{2} \uparrow$

$\mathrm{Fe}_{2} \mathrm{O}_{3} \cdot x \mathrm{H}_{2} \mathrm{O}(\mathrm{s}) \rightarrow \mathrm{Fe}_{2} \mathrm{O}_{3}(\mathrm{~s})+x \mathrm{H}_{2} \mathrm{O}(g)$

$\mathrm{Fe}, \mathrm{Cu}$

$\mathrm{Zn}, \mathrm{Al}$

$\mathrm{Al}, \mathrm{Zn}$

$\mathrm{Zn}, \mathrm{Cu}$