A solution that may contain \(\mathrm{Cu}^{2+}, \mathrm{Bi}^{3+},
\mathrm{Sn}^{4+},\) or \(\mathrm{Sb}^{3+}\) ions is treated with thioacetamide in
an acid medium. The black precipitate that forms is partly soluble in strongly
alkaline solution. The precipitate that remains is soluble in \(6 \mathrm{M}
\mathrm{HNO}_{3}\) and gives only a blue solution on treatment with excess
\(\mathrm{NH}_{3}\). The alkaline solution, when acidified, produces an orange
precipitate. On the basis of this information, which ions are present, which
are absent, and which are still in doubt? (As with Group I, evidence other
than confirmatory tests may show the presence or absence of an ion.)
Present ____________
Absent ____________
In doubt ____________
