(a) Write method will you use to reduce the following ? Explain by giving a suitable example.
(i) Oxides of less reactive metals
(ii) Oxides of moderately reactive metals
(iii) Oxides of highly reactive metals.
(b) The reaction between metal 'X' and `Fe_(2)O_(3)` is highly exothermic and is used to join railway tracks.
(i) Identify metal 'X' and name the reaction.
(ii) Write the chemical equation of its reaction with `Fe_(2)O_(3)`.

Explanation

(a) (i) Oxides of less reactive metals can be reduced either by auto-reduction or upon heating. For example,
`2Cu_(2)O + Cu_(2)S overset("heat")rarr6Cu + SO_(2)`
`2HgO overheat("heat")rarr 2Hg + O_(2)`
(ii) Oxides of moderately reactive metals can be reduced with coke. This is known as smelting. For example,
`ZnO + C overset("heat")rarrZn + CO`
`PbO + C overset("heat")rarr Pb + CO`
(iii) Oxides of highly reactive are reduced by electrolytic reduction.
`Al_(2)O_(3) ("molten")rarr underset(("cathode"))(2Al^(3+)) +underset(("Anode"))(3O^(2-))`
At cathode : `Al^(3+) + 3e^(-) rarrAl`.
At anode : `O^(2-) rarr O(1//2O_(2))+2e^(-)`
(b) (i) The metal 'X' is aluminium. The reaction is known as thermit reaction.
(ii) `Fe_(2)O_(3) + 2Al overset("heat")rarr Al_(2)O_(3) + 2Fe`