Analytical Chemistry Question 136
Question: A solution of metal ion when treated with KI, gives a red precipitate that dissolves in excess of KI to give a colorless solution. Moreover, the solution of metal ion on treatment with a solution of cobalt (II) thiocyanate gives rise to a deep blue crystalline precipitate. The metal ion is
Options:
A) $ P{b^{2+}} $
B) $ H{g^{2+}} $
C) $ C{u^{2+}} $
D) $ C{o^{2+}} $
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Answer:
Correct Answer: B
Solution:
[b] $ H{g^{2+}}+{I^{-}}\to HgI_2 $ (Scarlet red ppt.) $ HgI_2+2{I^{-}}\to {{[HgI_4]}^{2-}} $ (Soluble) $ H{g^{2+}}+Co{{(SCN)}_2}\to Co[Hg{{(SCN)}_4}] $ (Deep blue crystalline ppt.)
BETA
