(i) Carbon cannot be used as reducing agent to obtain Mg from MgO. Why ?
(ii) How is sodium obtained from molten sodium chloride ? Give equations of the reactions.
(iii) How is copper obtained from its sulphide ore ? Give equations of the reactions.

Explanation

(i) Mg has more affinity for oxygen than carbon.
(ii) Electrolytic reduction process of molten NaCl.
At cathode : `2Na^(+) + 2e^(-) rarr 2Na`
At anode : `2Cl^(-) rarr Cl_(2) + 2e`
(iii) `2Cu_(2)S + 3O_(2) rarr 2Cu_(2)O + 2SO_(2)`
`2Cu_(2)O + Cu_(2)S rarr 6Cu + SO_(2)`