Refractory materials are generally used in furnaces because

Which of the following changes involve more than two metallurgical processes?

In the equation: $M + 8CN^{-} + 2H_2O + O_2 \rightarrow 4[M(CN)_2]^- + 4OH^{-}$,metal $M$ is

Match the items under List-$I$ with the compounds/elements from the List-$II$. Select the correct answer from the sets $(a), (b), (c)$ and $(d)$.

List-$I$	List-$II$
$(i)$ Explosive	$(A)$ $NaN_3$
$(ii)$ Artificial gem	$(B)$ $Fe_3O_4$
$(iii)$ Self reduction	$(C)$ $Sn$
$(iv)$ Magnetic material	$(D)$ $Al_2O_3$
	$(E)$ $Pb(N_3)_2$
	$(F)$ $Fe_2O_3$
	$(G)$ $Cu$
	$(H)$ $SiC$

Extraction of copper from copper pyrite $CuFeS_2$ involves:
$A$. Crushing followed by concentration of the ore by froth-flotation
$B$. Removal of iron as slag
$C$. Self-reduction step to produce 'blister copper' following evolution of $SO_2$
$D$. Refining of 'blister copper' by carbon reduction

The alloy,which contains $95 \%$ aluminium and small amounts of copper,magnesium and manganese is . . . . . .