In group separation, before precipitating out group III metal ions as hydroxides, it is necessary to boil then solution of the salt mixture with a few drops of concentrated `HNO_(3)` is treated. This is done to convert:

Options

A. `Co^(2+)` to `Co^(3+)`
B. `Fe^(2+)` to `Fe^(3+)`
C. `Mn^(2+)` to `MnO_(4)^(-)`
D. `Cr^(3+)` to `CrO_(4)^(2-)`

Answer

B

Explanation

This is usually done ot convert `Fe^(2+)` to `Fe^(3+)` because `Fe^(III)` hydroxides are insoluble which can be separated to a large extent from more soluble than `Fe^(II)` hydroxides.