When `NH_(4)Cl` is not used together with `NH_(4)OH` in group-III reagent which of the following cation will not be precipitated?

Options

A. `Fe^(2+)`
B. `Cr^(3+)`
C. `Zn^(2+)`
D. `NH_(3)` soln.

Answer

D

Explanation

In the absence of `NH_(4)^(+)` ions or `NH_(4)Cl`, dissociation of `NH_(4)OH` is large i.e., concentration of `OH^(-)` is considerable to increase ionic products of hydroxides of `Fe^(2+),Cr^(3+) and Zn^(2+)` from their respective `K_(sp)` valeus, hence they will precipitate in `III^(rd)` group. however, `Ba(OH)_(2)` is soluble due to high `K_(sp)` value.