In which of the following metals extraction,impurities are removed as slag?
$i.$ $Al$ $\quad$ $ii.$ $Fe$
$iii.$ $Cu$ $\quad$ $iv.$ $Zn$
The correct option is

In aluminium extraction by the Bayer process, alumina is extracted from bauxite by sodium hydroxide at high temperature and pressure: $Al_2O_{3(s)} + 2 OH^-_{(aq)} + 3 H_2O_{(l)} \rightarrow 2 [Al(OH)_4]^-_{(aq)}$. Solid impurities such as $Fe_2O_3$ and $SiO_2$ are removed and then $[Al(OH)_4]^-$ is reprecipitated: $2 [Al(OH)_4]^-_{(aq)} \rightarrow Al_2O_3 \cdot 3 H_2O_{(s)} + 2 OH^-_{(aq)}$. In the industrial world:

What is the percentage of carbon in steel?

Match the alloys in Column $A$ with their uses in Column $B$:

Column $A$	Column $B$
$(1)$ Stainless steel	$(a)$ Riveting
$(2)$ Bronze	$(b)$ Making artifacts
$(3)$ Nitinol	$(c)$ Making coins
$(4)$ German silver	$(d)$ Making musical instruments
	$(e)$ Making surgical instruments

Which of the following processes is not used for the extraction of spelter from zinc blende?

One of the constituents of German silver is: