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.

Consider the following metallurgical processes:
$I$. Heating impure metal with $CO$ and distilling the resulting volatile carbonyl (b.p. $43 \ ^oC$) and finally decomposition at $150 \ ^oC - 200 \ ^oC$ to get the pure metal.
$II$. Heating the sulphide ore in air until a part is converted to oxide and then further heating in the absence of air to let the oxide react with unchanged metal sulphide.
$III$. Electrolysis of the molten electrolyte containing approximately equal amounts of the metal chloride and $NaCl$ to obtain the metal.
The processes used for obtaining magnesium,nickel and copper are respectively:

Which among the following statement$(s)$ is(are) true for the extraction of aluminium from bauxite?
$A$. Hydrated $Al_2O_3$ precipitates,when $CO_2$ is bubbled through a solution of sodium aluminate.
$B$. Addition of $Na_3AlF_6$ lowers the melting point of alumina.
$C$. $CO_2$ is evolved at the anode during electrolysis.
$D$. The cathode is a steel vessel with a lining of carbon.

Explain the following:
$(a)$ $CO_2$ is a better reducing agent below $710 \ K$ whereas $CO$ is a better reducing agent above $710 \ K$.
$(b)$ Generally,sulphide ores are converted into oxides before reduction.
$(c)$ Silica $(SiO_2)$ is added to the sulphide ore of copper in the reverberatory furnace.
$(d)$ Carbon and hydrogen are not used as reducing agents at high temperatures for certain metals.
$(e)$ Vapour phase refining method is used for the purification of $Ti$.

Consider the following statements:
$(i)$ Froth flotation technique is used to concentrate sulphide ore.
$(ii)$ Froth flotation technique is based upon differential wettability of ore and impurity in water.
$(iii)$ Red Bauxite is concentrated by Bayer's process.
$(iv)$ Carbon is used as a reducing agent during the extraction of zinc from zinc blende.
Which of the following statements are correct?

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