Question: Which of the oxide groups among the following cannot be reduced by carbon :-
$\mathrm{Fe}_{2} \mathrm{O}_{3}, \mathrm{ZnO}$
$\mathrm{PbO}, \mathrm{Fe}_{2} \mathrm{O}_{4}$
$\mathrm{Cu}_{2} \mathrm{O}, \mathrm{SnO}_{2}$
$\mathrm{CaO}, \mathrm{K}_{2} \mathrm{O}$
Correct Option: , 4
Solution:
More reactive metal such as K and "Ca" etc. can be used by electrolytic reduction method but
not by carbon reduction method.
