X + NaOH --> Y(aq) --> yellow solution?

Question

it is a MCQ question , im not sure which one . From question ,

Y(aq) added with Fe(2+) aq will give us yellow solution . X could be

A) . MgO B).Al2O3 C) SiO2 D) Cl2O7

i know it cant be MgO since it is basic oxide .And I believe the yellow solution must have something to do with oxidation of F2(2+) to Fe(3+) . I know Al(3+) cannot oxidise Fe(2+) . So is it C or D ?

please note that it is not Cr2O7 but Cl2O7 (it is chloride not dicromate )

Answer 1

The only oxidizing agent is Cl2O7

Cl2O7 is the anhydride of HClO4, so

Cl2O7+ 2NaOH -> 2NaClO4 + H2O

perchlorate is a very strong oxidizing agent so it will readily oxidize Fe+2 to Fe+3 while it will become Cl-.

Answer 2

check standard potential table in data booklet, seems like Cr2O7 2- is a stronger oxidizing agent than Fe3+, therefore the answer is D.