How do you differentiate between `Fe^(3+) and Cr^(3+)` in qualitative analysis group III ?

Options

A. By taking excess of `NH_4OH`
B. By increasing `NH_4^(+)` ion concentration
C. By decreasing `OH^(-)` ion concentration
D. Both (B) and (C).

Answer

D

Explanation

`K_(sp)` of `Fe(OH)_3` is less than `K_(sp)` of `Cr(OH)_3` . Therefore , `Fe^(3+)` is precipitated at lower `[OH^(-)]`