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# Hall-Heroult's process is given by "

Question:

Hall-Heroult's process is given by "

1. $\mathrm{Cr}_{2} \mathrm{O}_{3}+2 \mathrm{Al} \rightarrow \mathrm{Al}_{2} \mathrm{O}_{3}+2 \mathrm{Cr}$

2. $\mathrm{Cu}^{2+}$ (aq.) $+\mathrm{H}_{2}(\mathrm{~g}) \rightarrow \mathrm{Cu}(\mathrm{s})+2 \mathrm{H}^{+}$(aq)

3. $\mathrm{ZnO}+\mathrm{C} \stackrel{\text { Coke,1673K }}{\longrightarrow} \mathrm{Zn}+\mathrm{CO}$

4. $2 \mathrm{Al}_{2} \mathrm{O}_{3}+3 \mathrm{C} \rightarrow 4 \mathrm{Al}+3 \mathrm{CO}_{2}$

Correct Option: , 4

Solution:

In Hall-Heroult's process is given by

$2 \mathrm{Al}_{2} \mathrm{O}_{3}+3 \mathrm{C} \longrightarrow 4 \mathrm{Al}+3 \mathrm{CO}_{2}$

$2 \mathrm{Al}_{2} \mathrm{O}_{3}(\ell) \rightleftharpoons 4 \mathrm{Al}^{3+}(\ell)+6 \mathrm{O}^{2 \Theta}(\ell)$

At cathode :- $4 \mathrm{Al}_{(\ell)}^{3+}+12 \mathrm{e}^{\Theta} \rightarrow 4 \mathrm{Al}(\ell)$

At Anode : $6 \mathrm{O}_{(\ell)}^{2 \Theta} \rightarrow 3 \mathrm{O}_{2}(\mathrm{~g})+12 \mathrm{e}^{\Theta}$

$3 \mathrm{C}+3 \mathrm{O}_{2} \rightarrow 3 \mathrm{CO}_{2}(\uparrow)$