Spiegeleisen is an alloy of

In the leaching of $Ag_2S$ with $NaCN$,a stream of air is also passed. This is because of:

For the following statements,mark $T$ for true and $F$ for false statement.
Statement $1$: $SnO_2 +$ wolframite,in this $SnO_2$ is magnetic while wolframite is non-magnetic in nature.
Statement $2$: Argentite ore is concentrated by froth floatation method.
Statement $3$: Copper and lead ores are reduced by self-reduction method.
Statement $4$: In metallurgy of $Fe$,$CO$ is used as a reducing agent at low temperature.

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

In the Ellingham diagram,the plot is drawn between:

Identify the correct statements from the following:
$(i)$ In the extraction of $Ag$ and $Au$,zinc is used as a reducing agent.
$(ii)$ Impure zinc can be refined by distillation method.
$(iii)$ Malachite is an ore of nickel.