In the wet tests for detection of various cations by precipitation, $$\mathrm{Ba}^{2+}$$ cations are detected by obtaining precipitate of

When a solution of mixture having two inorganic salts was treated with freshly prepared ferrous sulphate in acidic medium, a dark brown ring was formed whereas on treatment with neutral $$\mathrm{FeCl}_{3}$$, it gave deep red colour which disppeared on boiling and a brown red ppt was formed. The mixture contains :

Formation of which complex, among the following, is not a confirmatory test of $$\mathrm{Pb}^{2+}$$ ions :

In the wet tests for identification of various cations by precipitation, which transition element cation doesn't belong to group IV in qualitative inorganic analysis?