question_answer

Which of the following reactions will give blue colour Precipitation?

(I) \[3C{{o}^{2+}}+{{[Fe{{(CN)}_{6}}]}^{3-}}\xrightarrow{{}}\]

(II) \[C{{o}^{2+}}+2SC{{N}^{\Theta }}\xrightarrow{{}}\]

(III) \[A{{l}^{+3}}+8\]Hydroxyquinoline \[\xrightarrow{{}}\]

(IV) \[C{{o}^{2+}}+\alpha -nitroso-\beta -naphthol\xrightarrow{{}}\]

A) I, II            

B)                    II, III                    

C)   I, II, IV                

D)        II, IV

Correct Answer: B

Solution :

[b] (I) \[(I)\xrightarrow{{}}\underset{reddish\,\,brown\,\,ppt.}{\mathop{C{{o}_{3}}{{[Fe{{(CN)}_{6}}]}_{2}}}}\,\] \[(II)\xrightarrow{{}}\underset{Blue\,\,colour}{\mathop{{{[Co{{(SCN)}_{4}}]}^{2-}}}}\,\] (III) (IV)