Name oxide of one metal which is reduced by (give equation).
(i) reduction with carbon.
(ii) electrolytic reduction.
(iii) reduction with heat alone.

(i) On heating, cupric oxide, ferric oxide, zinc oxide get reduced to copper, iron, zinc metals respectively, in the presence of carbon as a reducing agent.

$$\begin{gathered} 2\mathrm{CuO}+\mathrm{C}\stackrel{\mathrm{Heat}}{\to }2\mathrm{Cu}+{\mathrm{CO}}_2 \\ \mathrm{Cupric}\mathrm{oxide}\mathrm{Carbon}\mathrm{Copper}\mathrm{Carbon}\mathrm{dioxide} \\ {\mathrm{Fe}}_2{\mathrm{O}}_3+3\mathrm{C}\stackrel{\mathrm{Heat}}{\to }2\mathrm{Fe}+3\mathrm{CO} \\ \mathrm{Ferric}\mathrm{oxide}\mathrm{Carbon}\mathrm{Iron}\mathrm{Carbon}\mathrm{monoxide} \\ 2\mathrm{ZnO}+\mathrm{C}\stackrel{\mathrm{Heat}}{\to }2\mathrm{Zn}+{\mathrm{CO}}_2 \\ \mathrm{Zinc}\mathrm{oxide}\mathrm{Carbon}\mathrm{Zinc}\mathrm{Carbon}\mathrm{dioxide} \end{gathered}$$

(ii) Aluminium oxide undergoes electrolysis and forms aluminium at the cathode and oxygen at the anode.

$$\begin{gathered} {\mathrm{Al}}_2{\mathrm{O}}_3\stackrel{\mathrm{Electrolysis}}{\to }2{\mathrm{Al}}^{3+}+3{\mathrm{O}}^{2-} \\ \mathrm{At}\hspace{0.17em}\mathrm{cathode}:{\mathrm{Al}}^{3+}+3{\mathrm{e}}^{-}\to \mathrm{Al}\left(\mathrm{reduction}\right) \\ \mathrm{At}\mathrm{anode}:2{\mathrm{O}}^{2-}\to {\mathrm{O}}_2+4{\mathrm{e}}^{-} \end{gathered}$$

(iii) When mercuric oxide is heated strongly, it decomposes to form mercury and liberates oxygen.

$$\begin{gathered} 2\mathrm{HgO}\underset{\mathrm{Decompose}}{\overset{\mathrm{Heat}}{\to }}\mathrm{Hg}+{\mathrm{O}}_2 \\ \mathrm{Mercuric}\mathrm{oxide}\mathrm{Mercury}\mathrm{Oxygen}\mathrm{gas} \end{gathered}$$ 2HgO −→−−−−DecomposeHeat 2Hg + 2