alleryWhy is conc. HNO3 added to the original solution before group III precipitation?
ATo remove H2S fully
BTo dissolve Al(OH)3
CTo keep Zn2+ in solution
DTo oxidise Fe2+ to Fe3+
Answer & Solution
Correct answer: D. To oxidise Fe2+ to Fe3+
Nitric acid oxidises ferrous to ferric ions so that iron precipitates completely as Fe(OH)3 in group III.
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