Which metal is more reactive than magnesium $(Mg)$?

Give reasons for the following:
$(i)$ Gold and platinum are used in jewellery.
$(ii)$ Copper cannot displace hydrogen from dilute acids.
$(iii)$ Stainless steel does not rust easily.
$(iv)$ Metals can be given different shapes according to our needs.
$(v)$ Zinc does not give hydrogen gas on reacting with $HNO_3$.

What is the chemical formula of alumina?

Name two metals in each of the following cases:
$(i)$ Metals that are stored in kerosene.
$(ii)$ Metals that are alloyed with iron to make stainless steel.
$(iii)$ Metals which are highly malleable and ductile.

$2Na_{(s)} + 2H_2O_{(l)} \longrightarrow ?$

Which process occurs at the cathode during the process of electrolysis?