To avoid the precipitate of hydroxide of `Ni^(2+),Co^(2+),Zn^(2+)` and `Mn^(2+)` along with these of `Fe^(3+),Al^(3+)` and `Cr^(3+)` the third group solution should be

Options

A. Heated with a few drop of cone `HNO_(3)`
B. Treated with excess of `NH_(4)CI`
C. Conccotrated
D. None of these

Answer

b

Explanation

The presence of `NH_(4)CI` in excess reducts degree of dissociation of `NH_(4)OH` to a considerable amount and thas `[OH^(Theta)]` just sufficient to cross ever the and ionic concentration product of hyddroxide of group III elements to their `K_(sp)`